Determination of the blending parameters of ternary blends containing a terpolymer as a component copolymer by multivariate analysis of NMR data

Heat-resistant ABS resin, an industrial polymer material, is generally prepared by mixing AN/MS bipolymer and/or AN/ST/MS terpolymer with the matrix of ABS resin, where AN, ST and MS denote acrylonitrile, styrene and α-methylstyrene, respectively. In order to predict the thermal properties of ABS resins, it is important to know which copolymers are blended and in what ratio. In this study, statistical structural analysis was performed on polymer blends consisting of AN/ST bipolymer, AN/MS bipolymer and AN/ST/MS terpolymer to predict blending parameters for heat-resistant ABS resin. Nuclear magnetic resonance (NMR) spectral data of the polymer blends were used as explanatory variables to determine the chemical composition and mole fraction of the component copolymers. Partial least-squares (PLS) regression and least absolute shrinkage and selection operator (LASSO) regression were used as the exploratory techniques. The use of 1H NMR spectral data showed poor prediction, probably because of low resolution due to the narrow spectral width. Accordingly, 13C NMR spectra, which have wider spectral widths, were used, resulting in the successful prediction of the blending parameters of the ternary blends containing a terpolymer as a component. It should be noted that it was not necessary to obtain the NMR spectra of all the polymer blends as the explanatory variables, i.e., linear combinations of the NMR spectra of the component copolymers were sufficient.

アクリロニトリル(AN)/スチレン(ST)，AN/α-メチルスチレン(MS)，およびAN/ST/MS共重合体の3元ブレンドのブレンドパラメータの推定を2元ブレンドの13C NMRスペクトルの多変量解析により行った．トレーニングデータに13C NMRスペクトルの線形結合を利用できることがわかった．


Synthesis of Alkynyl Spacer-Containing Chiral Polyguanidines and Their Noncovalent Modification for Organocatalyst Design


Synthesis of photodegradable polyesters from bio-based 3,4-dimethoxycinnamic acid and investigation of their degradation behaviors


Anionic polymerization of methyl methacrylate and chain-end modification via terminal-selective transesterification with bulky zincate

The anionic polymerization of methyl methacrylate (MMA) was investigated using dilithium tetra-tert-butylzincate (TBZL), which is a bulky zincate, as an initiator. Poly(methyl methacrylate) (PMMA) with a narrow molecular weight distribution was obtained by conducting the polymerization in toluene at -80 °C. Chain-end analysis revealed the formation of PMMA with a tert-butyl group at the α-end and a hydrogen atom at the ω-end. These results suggest the living nature of the present polymerization. However, a prolonged polymerization time or elevated temperature caused backbiting reactions. Postpolymerization modification of the formed PMMA was also investigated using TBZL as a transesterification catalyst. Chain-end analysis revealed that terminal-selective transesterification occurred only at the monomeric unit at the terminating chain end. Therefore, TBZL appears to play dual roles in the production of chain-end-modified PMMA: an initiator for anionic polymerization and a catalyst for terminal-selective transesterification.

かさ高い亜鉛アート錯体がメタクリル酸メチルのアニオン重合開始剤および生成ポリマーの末端選択的エステル交換反応の触媒として働き，一つの触媒だけを用いて末端修飾ポリマーが合成できることを見出した．


Multivariate statistical analysis of 1H NMR data for binary and ternary blends of copolymers to determine the chemical composition and blending fractions of the components

Statistical 1H nuclear magnetic resonance (NMR) analysis was conducted for ternary blends of copolymers. Two out of three monomers, acrylonitrile, styrene, and α-methylstyrene, were radically polymerized to synthesize three kinds of copolymers that were mixed to prepare binary and ternary blends of the copolymers. The 1H NMR spectral matrix of the copolymers and their blends (explanatory variables) was combined with the blending parameter matrix (objective variables). Cross-validation with the least absolute shrinkage and selection operator regression confirmed that excellent regression models were constructed with the dataset composed of data for eight copolymers and forty-five binary blends to predict the blending parameters, such as the chemical composition and mole fraction of the component copolymers, in the binary blends. Accordingly, the models were applied to predict the blending parameters in the ternary blends, resulting in successful predictions with high accuracy. Other regularized regression models, such as Ridge regression and Elastic Net, were also examined.

アクリロニトリル，スチレンおよびα-メチルスチレンのうちの2つのモノマーからなる2元共重合体を合成し，その3元ブレンドの1H NMRスペクトルの多変量解析により，ブレンドパラメータを推定した．


Nuclear Magnetic Resonance Analysis of Hydrothermal Reactions of Ethyl- and Octylamine in Sub- and Supercritical Water

Hydrothermal reactions of aliphatic amines have recently gained importance in relation to the application of amines as film-forming corrosion inhibitors for steam-water cycles. The kinetics and mechanism of the hydrothermal reactions of ethylammomiun cation (EtAH) and -octylammonium cation (OctAH) were studied for comparison with the corresponding neutral amines to elucidate their reaction products and pathways at sub- and supercritical temperatures of 300-400 °C as model reactions of aliphatic ammonium cations. We analyzed the reaction of C-N-labeled EtAH using NMR spectroscopy and revealed that the initial hydrolysis to ethanol, known as the main path, is followed by the elimination reaction producing ethene and the disproportionation reaction giving diethylammonium cation. The OctAH yields octene and octanol, each of which isomerizes to thermodynamically more stable species as the major products. Comparisons were made between the reactions of the neutral amines and ammonium cations to highlight their different reactivity. The hydrolysis, alkene formation, and dehydration of alcohols to alkenes were all found to be accelerated at low pH. The formation of low-molecular-weight organic acids such as acetic acid and formic acid was not observed. These results indicate that the corrosion protection effect of film-forming amines will be maintained under practical conditions with pH values as high as around 9 to 10, and hence side reactions involving byproducts will be suppressed.


Immobilization of a flavin molecule onto poly(methacrylic acid)s and its application in aerobic oxidation catalysis: effect of polymer stereoregularity


Statistical determination of chemical composition and blending fraction of copolymers by multivariate analysis of 1H NMR spectra of binary blends of the copolymers

A chemometric approach for the quantitative structural analysis of binary blends of copolymers was conducted. Three types of copolymers were synthesized by radical emulsion copolymerization of two out of three monomers acrylonitrile, styrene, and α-methylstyrene to prepare three series of binary blends of these copolymers. Partial least-squares (PLS) regression and least absolute shrinkage and selection operator (LASSO) regression were conducted with datasets in which the 1H nuclear magnetic resonance (NMR) spectral matrix of the binary blends (explanatory variables) is combined with the blending parameter matrix (objective variables) of the binary blends. The blending parameters, such as chemical compositions and mole fractions of the component copolymers, were successfully predicted without any assignments of the 1H NMR signals through stepwise optimization of the objective and explanatory variables. LASSO regression exhibited higher accuracy than PLS regression, suggesting that the variable selection in LASSO regression was responsible for the improvement in the quantitative prediction.

アクリロニトリル，スチレンおよびα-メチルスチレンのうちの2つのモノマーからなる2元共重合体を合成し，その2元ブレンドの1H NMRスペクトルの多変量解析により，ブレンドパラメータを推定した．変数を段階的に最適化することにより，NMRシグナルの帰属なしに，共重合体成分の組成とブレンド比率を精度よく推定できることを見出した．


Determination of Monomer Reactivity Ratios from a Single Sample using Multivariate Analysis of the 1H NMR Spectra of Poly[(methyl methacrylate)-co-(benzyl methacrylate)]

Copolymers of methyl methacrylate (MMA) and benzyl methacrylate (BnMA) were prepared by conventional radical copolymerization in toluene at 70 °C. The 1H nuclear magnetic resonance (NMR) spectra of these copolymers were measured in various solvents at different temperatures. The signals of the methoxy protons in the MMA units and the benzyl protons in the BnMA units showed splitting mainly because of the triad monomer sequences when the temperature was increased to 150 °C in deuterated dimethyl sulfoxide. However, the splitting was not sufficient to determine the mole ratios of the triad sequences. Therefore, multivariate analysis was applied to the 1H NMR spectra of copolymers with various chemical compositions. Principal component analysis successfully extracted information on the polymer microstructures. Partial least-squares (PLS) regression successfully predicted the mole fractions of the diad monomer sequences. Then, the fractions of the diad sequences in an unknown sample prepared in benzene at 60 °C were predicted using PLS regression to determine the monomer reactivity ratios. Thus, the monomer reactivity ratios were successfully determined from a single sample using multivariate analysis of the 1H NMR spectra of copolymers of MMA and BnMA.

メタクリル酸メチル/メタクリル酸ベンジル共重合体の1H NMRスペクトルに多変量解析を適用することで，2連子モノマー連鎖分布を推定し，1つのサンプルからモノマー反応性比を求めることに成功した．


Cationic homopolymerization of trans-anethole in the presence of solvate ionic liquid comprising LiN(SO2CF3)2 and Lewis bases

Cationic homopolymerization of a biomass-derived monomer, trans-4-methoxy-β-methylstyrene (trans-anethole: Ane), was achieved with a combination of bis(trifluoromethylsulfonyl)imide and solvate ionic liquid comprising lithium bis(trifluoromethylsulfonyl)imide and a Lewis base, such as ethyl acetate and diisopropyl ether (iPr2O). The number-average molecular weight (Mn) of the obtained poly(Ane) reached 15.6 × 103 by adding iPr2O in toluene at 10 °C. The solubility of poly(Ane) varied drastically with a change of solvent: the polymers obtained in CH2Cl2 were not completely soluble in common organic solvents such as toluene, chloroform, and tetrahydrofuran, except for 1,1,2,2,-tetrachloroethane (C2H2Cl4) at 140 °C, whereas the polymers obtained in toluene were soluble in these solvents. The 1H NMR spectrum measured in C2D2Cl4 at 140 °C revealed that the stereostructure of poly(Ane) depended significantly on the solvent and the temperature: a polymer with a more regulated stereostructure was obtained from polymerization in CH2Cl2 at 40 °C than those obtained by polymerization in toluene at 10 °C.

植物由来モノマーの1つであるtrans-アネトールは，α,β-2置換ビニルモノマーであるため単独重合性が低い．本研究では，LiNTf2とルイス塩基からなる溶媒和イオン液体を添加することで，trans-アネトールの単独カチオン重合が進行することを見出した．また，溶媒をトルエンからCH2Cl2に変更すると，一般的な有機溶媒に不溶なポリマーが得られたが，高温NMR測定によって立体規則性が変化していることも明らかにした．


Hydrogen-Bond-Assisted Asymmetric Radical Cyclopolymerization of N-allyl-N- tert-butylacrylamide in the Presence of Chiral Tartrates

光学活性な酒石酸エステル存在下，N-アリル-N-tert-ブチルアクリルアミドのラジカル環化重合を行うと，光学活性なポリマーが得られることを見出した．比旋光度および円二色性スペクトルなどの光学特性や脱tert-ブチル化したポリマーのNMRスペクトルから，L-酒石酸エステルを添加すると(3S,4S)-transの立体構造を有する繰り返し単位が優先的に生成することがわかった．


De-tert-butylation of poly(N-tert-butyl-N-n-propylacrylamide): Stereochemical analysis at the triad level

NMRスペクトルから立体規則性を定量できないポリ(N-tert-ブチル-N-n-プロピルアクリルアミド)の脱tert-ブチル化反応を行うと，得られるポリ(N-n-プロピルアクリルアミド)の13C NMRから3連子立体規則性が定量できることを見出した．


Chemoselective radical polymerization of N-allylmethacrylamide with an aid of complexation with Li+ cation

LiNTf2存在化N-アリルメタクリルアミドのラジカル重合を行うと，Li+カチオンとの錯形成によって安定化されたラジカルとLi+カチオンとの錯形成によって活性化したモノマーとの間で化学選択的に重合が進行し，側鎖にアリル基を有する線状ポリマーが得られることを見出した．


Unusually large hysteresis in temperature-responsive phase-transition behavior of aqueous solutions of isotactic copolymers comprising N-ethylacrylamide and N-isopropylacrylamide

イソタクチックな立体構造を有するN-エチルアクリルアミド/N-イソプロピルアクリルアミド共重合体の水溶液が示す下限臨界溶液温度型相転移挙動について調べた．NIPAAm組成が13.9∼28.0 mol%の共重合体が約40℃の大きなヒステリシスを示すことを明らかにした．これは，これまで報告されている中で最も大きなヒステリシスである．光散乱による測定から，大きなヒステリシスが発現するメカニズムについて考察を行った．


NMR Analysis of Poly(Lactic Acid) via Statistical Models

The physical properties of poly(lactic acid) (PLA) are influenced by its stereoregularity and stereosequence distribution, and its polymer stereochemistry can be effectively studied by NMR spectroscopy. In previously published NMR studies of PLA tacticity, the NMR data were fitted to pair-addition Bernoullian models. In this work, we prepared several PLA samples with a tin catalyst at different L,L-lactide and D,D-lactide ratios. Upon analysis of the tetrad intensities with the pair-addition Bernoullian model, we found substantial deviations between observed and calculated intensities due to the presence of transesterification and racemization during the polymerization processes. We formulated a two-state (pair-addition Bernoullian and single-addition Bernoullian) model, and it gave a better fit to the observed data. The use of the two-state model provides a quantitative measure of the extent of transesterification and racemization, and potentially yields useful information on the polymerization mechanism.


High-Pressure and High-Temperature NMR Observation of Synthetic Polymers: High-Resolution Measurement Taking Advantage of Motional Narrowing in Sub-Critical Fluids

合成高分子の高圧高温NMR観測:亜臨界流体中の高い分子運動性を利用した高分解能測定

The Review of High Pressure Science and Technology


Thermally induced cationic polymerization of isobutyl vinyl ether in toluene in the presence of solvate ionic liquid

ラジカルとリチウムカチオンとの相互作用を利用して，イソブチルビニルエーテル(IBVE)のラジカル重合を試みた． LiN(SO2CF3)2(LiNTf2)およびメタクリル酸メチル(MMA)および酢酸ビニル(VAc)のようなエステル化合物をそれぞれLi+源およびLiNTf2の溶解剤として添加した．MMAおよびVAcなどのラジカル重合性モノマーが存在するにもかかわらずカチオン重合性IBVEのホモポリマーが得られた．期待とは異なり，ラジカル機構ではなくカチオン機構で重合が進行した．しかし，このカチオン重合は珍しいことがわかった．特に，重合収率は重合温度と共に増加した． 100℃では重合が進行したが，0℃などの低温では重合は起こらなかった．したがって，本系の挙動を「熱誘起カチオン重合」と定義した．熱誘発カチオン重合のメカニズムは明確ではないが，LiNTf2とルイス塩基との間に形成される溶媒和イオン液体との相互作用によって，成長カチオンが顕著に安定化されたと考えられる．


Multivariate analysis of 13C NMR spectra to extract information about monomer sequences in poly(methyl methacrylate-co-benzyl methacrylate)s prepared by various polymer reactions


Synthesis of aliphatic polycarbonates by irreversible polycondensation catalyzed by dilithium tetra-tert-butylzincate

Diethyl carbonate was reacted with phenol or 1,6-hexanediol with 5 mol% dilithium tetra-tert-butylzincate (TBZL) as a catalyst at 25 or 70 °C. The exchange reaction with phenol did not occur under these conditions, while that with 1,6-hexanediol did. Thus, polycondensation of diphenyl carbonate with 1,6-hexanediol was investigated. As expected, poly (hexamethylene carbonate) was obtained without removal of the by-product phenol. Conversion reached over 99% with increasing polymerization temperature. Additionally, 1,5-pentandiol and 1,9-nonanediol were also suitable diols for the polycondensation. Aliphatic polycarbonates with number-average molecular weights of 10,000 or more were obtained under optimum polymerization conditions. Polycondensation catalyzed by TBZL proceeded faster than that by titanium tetraisopropoxide, which is used as a general catalyst for polycondensation of diesters, dialkylcarbonates, and diphenyl carbonate with diols. Polycondensations with TBZL proceeded under atmospheric pressure in the presence of the by-product phenol. This polymerization system is expected to be applicable to various diols.

テトラ-tert-ブチル亜鉛酸ジリチウムを触媒とするエステル交換反応を利用して，脂肪族ポリカーボネートが合成できることを見出した．


NMR studies of water dynamics during sol-to-gel transition of poly (N-isopropylacrylamide) in concentrated aqueous solution

The focus of this work was on the significant changes in the water dynamics of aqueous poly (N-isopropylacrylamide) (PNIPAM) solution during sol-to-gel transition. Through the use of NMR (particularly two-dimensional 2H NMR T1-T2 relaxation) and rheology, we were able to show that below 34° C fast exchange occurs among free water and water molecules adsorbed on the surface of PNIPAM molecules. At 34° C, PNIPAM becomes aggregated; most of the water molecules are trapped in the PNIPAM aggregates, where water molecules with different dynamics are found. Above 34° C, PNIPAM molecules aggregate further to form a gel network; the free bulk water then becomes dominant at this stage. On the basis of these observations, a model where water molecules interact with PNIPAM in different ways during the transition was proposed. We believe that our experimental approach provides new information and fresh perspectives on the sol-to-gel transition of PNIPAM.

ポリ(N-イソプロピルアクリルアミド)の濃厚水溶液のゾルーゲル転移における水のダイナミクスを2D 2H T1-T2 NMR relaxation法を用いて調べた．相転移中に水が幾つかの状態を取りうることがわかり，水とポリマーとの相互作用について新しいモデルを提案した．


Effects of Syndiotacticity on the Dynamic and Static Phase Separation Properties of Poly(N-Isopropylacrylamide) in Aqueous Solution

The dynamic and static phase separation behavior in aqueous poly(N-isopropylacrylamide) (PNIPAM) solutions is highly sensitive to the tacticity of PNIPAM. We investigated the phase separation dynamics of aqueous solutions of PNIPAM with different tacticities (atactic and syndiotactic-rich types) and found that the phase separation dynamics of syndiotactic-rich PNIPAM was much different from that of atactic-type PNIPAM. First, phase separation in syndiotactic-rich PNIPAM was faster. Second, there was a critical point (Ccp) in the concentration dependence of the phase separation rate: the phase separation accelerated dramatically when the solution concentration was higher than 2.0 wt % (= Ccp). Third, syndiotactic-rich PNIPAM required a higher thermal energy for phase separation compared to atactic PNIPAM. Such behavior can be explained on the basis of the high hydrophobicity of syndiotactic-rich PNIPAM in a dehydrated state and a diffusion-controlled aggregation model. The present study shows that precise control of the stereoregularity will open new channels toward the design and development of stimuli-responsive-polymer-based smart materials.


Multivariate analysis of 13C NMR spectra of branched copolymers prepared by initiator-fragment incorporation radical copolymerization of ethylene glycol dimethacrylate and tert-butyl methacrylate

In this paper, we report chemometric approach for structural analysis of branched copolymers. To evaluate chemical compositions and degree of branching (DB) values in branched copolymers, multivariate analyses, such as principal component analysis (PCA) and partial least-squares (PLS) regression, were applied to the 13C nuclear magnetic resonance (NMR) spectra of the carbonyl carbons of the copolymers prepared by initiator-fragment incorporation radical copolymerization of ethylene glycol dimethacrylate (EGDMA) and tert-butyl methacrylate (TBMA) with dimethyl 2,2'-azobisisobutyrate (MAIB). PCA successfully extracted information on monomeric units, such as EGDMA units, TBMA units and MAIB fragments, the last of which were incorporated via initiation and primary radical termination. The chemical compositions and the DB values of the copolymers were predicted by PLS regression. Proper selection of a training set was found to be important for the prediction: the training set has to contain branched copolymers along with poly(EGDMA) and poly(TBMA). PLS regression using the appropriate training set allowed us to predict quantitatively the chemical compositions and DB values, without any assignments of the individual peaks.

開始剤組込みラジカル共重合で合成した分岐ポリマーのNMRスペクトルに多変量解析を適用することで，組成や分岐度などの構造情報を定量的に解析できることを明らかにした．


Efficient acylation and transesterification catalyzed by dilithium tetra-tert-butylzincate at low temperatures


Syndiotactic- and heterotactic-specific radical polymerization of N-n-propylmethacrylamide complexed with alkali metal ions

LiNTf2を含むアルカリ金属塩存在下でN-n-プロピルアクリルアミドのラジカル重合を行った．アルカリ金属塩を添加すると，得られるポリマーの収率と分子量が著しく増加した．さらに，LiNTf2存在下では溶媒によって立体特異性が変化した．NMR測定からモノマー/Li+錯体の化学量論比が立体特異性を決める要因であることがわかった．ESR測定からLi塩の添加によって成長反応速度定数が増加し，停止反応速度定数が低下することがわかった．また，立体規則性が相転移挙動に影響を及ぼすこともわかった．例えば，シンジオタクチックポリマーではrr3連子の増加とともに相転移温度が低下した．また，ヘテロタクチックポリマーではmr3連子の増加とともにヒステリシスが増加した．


Dual role for alkali metal cations in enhancing the low-temperature radical polymerization of N,N-dimethylacrylamide

The radical polymerization of N,N-dimethylacrylamide (DMAAm) has been investigated in the presence of several alkali metal salts, including lithium bis(trifluoromethanesulfonyl)imide (LiNTf2). The addition of an alkali metal salt led to a significant increase in the yield and molecular weight of the resulting polymer. NMR analysis of mixtures of DMAAm and LiNTf2 suggested that DMAAm was being activated by the coordination of Li+ to its C=O group. Electron spin resonance analysis of the DMAAm polymerization in the presence of LiNTf2 suggested that the propagating radical was being stabilized by Li+ through a single-electron lithium bond, because a signal for the propagating radical of the acrylamide derivatives was observed for the first time in solution when LiNTf2 was added. Based on these results, we have proposed a mechanism for this polymerization, where the propagation steps occur between a lithium ion-stabilized propagating radical and a lithium ion-activated incoming monomer. Furthermore, polymers with a wide range of stereoregularities, such as isotactic, syndiotactic and heterotactic systems, were successfully prepared using this method by carefully selecting the appropriate combination of solvent and alkali metal salt.

LiNTf2を含むアルカリ金属塩存在下でN,N-ジメチルアクリルアミドのラジカル重合を行った．アルカリ金属塩を添加すると，得られるポリマーの収率と分子量が著しく増加した．モノマー/Li塩混合物のNMR測定から，Liカチオンがカルボニル基に配位することでモノマーが活性化されていることが示唆された．ESRを測定したところ，成長活性種のシグナルが観測された．アクリルアミド誘導体のラジカル重合で成長活性種のESRシグナルを溶液状態で観測した初めての例であることから，1電子Li結合によって成長ラジカルが安定化されていることが示唆された．以上の結果から，本重合系ではLiカチオンによって安定化されたラジカルとLiカチオンによって活性化されたモノマーとの間で成長反応が進行していると考えられる．さらに，溶媒とアルカリ金属塩の適切な組み合わせを選択することで，イソタクチック，シンジオタクチック，ヘテロタクチックのような幅広い立体規則性のポリマーが得られることも見出した．


Ring-opening polymerization of epsilon-caprolactone with dilithium tetra-tert-butylzincate under mild conditions


Hydrogen-bond-assisted isotactic-specific radical polymerization of N-vinyl-2-pyrrolidone with tartrate additives in toluene at low temperatures: high-resolution 1H NMR analysis

A diethyl L-tartrate (L-EtTar)-assisted radical polymerization of N-vinyl-2-pyrrolidone has been developed as the first reported example of the synthesis of isotactic-rich poly(N-vinyl-2-pyrrolidone) (PVP). The addition of L-EtTar in toluene at temperatures of -40 °C and lower led to a significant increase in the polymer yield by one order of magnitude compared with the reaction in the absence of L-EtTar. Decreasing the polymerization temperature led to increases in the isotacticity of the PVP, with the mm triad reaching 66.4% at -93 °C. 1H NMR measurement at 920 MHz was conducted to establish a reliable strategy for quantifying the triad tacticities. High-temperature NMR measurements at 250 °C were performed using a specially-designed NMR probe, which led to dramatic narrowing of the 1H line width.

N-ビニル-2-ピロリドンの低温ラジカル重合系に酒石酸ジエチルを添加すると，収率や分子量が増加するとともにイソタクチシチーも増加することを見出した．また，1H NMRの測定条件を最適化することで，3連子立体規則性を定量することに成功した．


Effect of composition and stereoregularity on phase-transition behavior of aqueous N-ethylacrylamide/N-n-propylacrylamide copolymer solutions

Radical copolymerizations of N-ethylacrylamide and N-n-propylacrylamide (NNPAAm) at various ratios were carried out at -40 °C, in toluene in the presence of 3-methyl-3-pentanol, or in N-ethylacetamide. Syndiotactic-rich copolymers with racemo diad contents of 67.1 70.2%, and isotactic-rich copolymers with meso diad contents of 60.9 64.5% were prepared. Syndiotactic-rich copolymers with NNPAAm compositions of ≥92.9 mol% exhibited large hystereses in the phase-transition temperatures of their aqueous solutions. Isotactic-rich copolymers with NNPAAm compositions of 39.2 67.6 mol% exhibited large hystereses in the phase-transition temperatures of their aqueous solutions. Those of composition >67.6 mol% were insoluble in water. Stereosequence analysis suggested that isotactic sequences favored intramolecular hydrogen bonding between contiguous NNPAAm units, more than syndiotactic sequences. Enhanced intramolecular hydrogen bonding in isotactic sequences was responsible for the large hystereses and insolubility of isotactic-rich copolymers with high NNPAAm compositions.

N-エチルアクリルアミドとN-n-プロピルアクリルアミドのラジカル共重合を行い，イソタクチックおよびシンジオタクチックコポリマーを合成した．得られたコポリマーの水溶液の相転移挙動を調べたところ，シンジオタクチックよりもイソタクチックな連鎖の方が大きなヒステリシスを示しやすいことを見出した．


Isotactic-specific anionic polymerization of N-isopropylacrylamide with dilithium tetra-tert-butylzincate in the presence of a fluorinated alcohol or Lewis acid

The polymerization of N-isopropylacrylamide (NIPAAm) with dilithium tetra-tert-butylzincate (TBZL) has been investigated in toluene at low temperatures in the presence of alkyl and fluorinated alcohols. Of the alcohols examined, 1,1,1,3,3,3-hexafluoro-2-propanol induced isotactic specificity and accelerated the polymerization process, affording the corresponding poly(NIPAAm)s with meso (m) diad contents of 82% in relatively high yields. It is worthy of note that the introduction of a fluorinated alcohol, which is typically used as an inhibitor in conventional anionic polymerization processes, enabled control over the stereospecificity and rate of the anionic polymerization of NIPAAm when TBZL was used as an initiator. Yttrium trifluoromethanesulfonate also induced isotactic specificity in the NIPAAm polymerization process in methanol and gave poly(NIPAAm) with an m diad content of 88% in high yield.

かさ高いアート錯体であるTBZLによるN-イソプロピルアクリルアミドのアニオン重合において，1,1,1,3,3,3-ヘキサフルオロ-2-プロパノールやイットリウムトリフラートなどを添加すると，イソタクチック特異性が誘起されることを見出した．


Statistical Determination of Chemical Composition and Monomer Sequence Distribution of Poly(methyl methacrylate-co-tert-butyl methacrylate)s by Multivariate Analysis of 13C NMR Spectra

To evaluate chemical compositions and heterogeneity of comonomer sequences in methyl methacrylate (MMA)-tert-butyl methacrylate (TBMA) copolymers, multivariate analysis was applied to the 13C nuclear magnetic resonance (NMR) spectra of the carbonyl, backbone quaternary and α-methyl carbons of the copolymers. A better linear relationship was found between the first principal component score and the chemical composition in copolymers than was found between the results from spectra of the carbonyl and backbone quaternary carbons. The chemical compositions of 16 copolymers were successfully predicted by partial least squares regression (PLSR). The second principal component was found to reflect the fraction of MMA-TBMA hetero dyad sequence. Dyad sequence distributions of copolymers that were obtained at higher conversions were successfully determined by PLSR with those of copolymers obtained at low conversions as a training set. Multivariate analysis using properly prepared samples provided us with quantitative information of chemical compositions and comonomer sequence distributions, without assignment of the 13C NMR resonance peaks.

メタクリル酸メチル-メタクリル酸tert-ブチル共重合体の13C NMRスペクトルに主成分分析を適用すると，共重合体中の組成やモノマー連鎖に関する情報を抽出することができた．また，個々のピークを帰属しなくても部分最小二乗回帰によって組成やモノマー連鎖を推定できることを見出した．


Application of Multivariate Analysis of NMR Spectra of Poly(N-isopropylacrylamide) to Assignment of Stereostructures and Prediction of Tacticity Distribution

In this paper, we report multivariate analyses, such as principal component analysis and partial least-squares regression, of NMR spectra of poly(N-isopropylacrylamide)s [poly(NIPAAm)s]. Principal component analysis successfully interpreted the assignments of NMR spectra of poly(NIPAAm)s in terms of stereostructures for the methine carbons at triad levels and for the methylene protons at tetrad levels. Furthermore, triad tacticity was successfully predicted by partial least-squares regression of 1H NMR spectra of the methine and methylene groups, although the low resolution of the signals of the methine protons confines determination of tacticities by conventional methods to the diad levels. Consequently, it is assumed that chemometric approaches are useful for assigning NMR spectra in terms of stereostructures and for predicting tacticity distributions.

poly(NIPAAm)のNMRスペクトルに多変量解析を適用し，立体規則性による帰属が説明できることや3連子立体規則性を推定できることを見出した．


Kinetic Hydrate Inhibition of Poly(N-isopropylacrylamide)s with Different Tacticities

Poly(N-isopropylacrylamide)s (PNIPAMs) and poly(N-isopropylmethacrylamide)s have been investigated recently as kinetic hydrate inhibitors (KHIs). Now, poly(N-isopropylmethacrylamide) is commercialized. These are usually made by standard radical polymerization methods, which do not allow for control over the polymer tacticity. For this study, PNIPAMs were synthesized using new polymerization methods, giving a fairly high degree of tacticity control. We report here results on the performance of different tacticities of PNIPAMs with similar molecular weights in KHI tests with natural gas in stirred autoclaves and on tetrahydrofuran (THF) structure II hydrate crystal growth. From the results, we can conclude that the polymer tacticity does affect the KHI performance of PNIPAMs. PNIPAM with a higher syndiotactic percentage performed better than PNIPAM with a lower syndiotactic percentage. Both polymers demonstrated some kind of crystal surface adsorption by affecting the morphology of the THF hydrate crystals.

立体規則性の異なるポリ(N-イソプロピルアクリルアミド)を速度論的水和物抑制剤として用いたところ，シンジオタクチックポリマーの方が高い抑制効果を示すことを見出した．


Syndiotactic- and Heterotactic-Specific Radical Polymerizations of N-n-Propyl-α-fluoroacrylamide and Phase-Transition Behaviors of Aqueous Solutions of Poly(N-n-propyl-α-fluoroacrylamide)

Radical polymerization of N-n-propyl-α-fluoroacrylamide (NNPFAAm) was investigated in several solvents at low temperatures in the presence or absence of Lewis bases, Lewis acids, alkyl alcohols, silyl alcohols, or fluorinated alcohols. Different effects of solvents and additives on stereospecificity were observed in the radical polymerizations of NNPFAAm and its hydrocarbon analogs such as N-isopropylacrylamide (NIPAAm) and N-n-propylacrylamide (NNPAAm); for instance, syndiotactic (and heterotactic) specificities were induced in radical polymerization of NNPFAAm in polar solvents (and in toluene in the presence of alkyl and silyl alcohols), whereas isotactic (and syndiotactic) specificities were induced in radical polymerizations of the hydrocarbon analogs under the corresponding conditions. In contrast, heterotactic specificity induced by fluorinated alcohols was further enhanced in radical polymerization of NNPFAAm. The effects of stereoregularity on the phase-transition behaviors of aqueous solutions of poly(NNPFAAm) were also investigated. Different tendencies in stereoregularity were observed in aqueous solutions of poly(NNPFAAm)s from those in solutions of the hydrocarbon analogs such as poly(NIPAAm) and poly (NNPAAm).

N-n-プロピル-α-フルオロアクリルアミドのラジカル重合を極性溶媒中低温で行うと，シンジオタクチックポリマーが得られること，フッ素化アルコール存在下トルエン中低温で行うとヘテロタクチックポリマーが得られることを見出した．また，立体規則性がポリマー水溶液の相転移に影響を及ぼすことも見出した．

Journal of Polymer Science Part A: Polymer Chemistry


Syndiotactic specific radical polymerization of N-isopropylacrylamide in toluene at low temperatures in the presence of silyl alcohols

The radical polymerization of N-isopropylacrylamide was carried out in toluene at low temperatures in the presence of silyl alcohols, such as triethylsilanol. Poly(N-isopropylacrylamide) with a racemo dyad content of 75% was obtained at - 80 °C with a 4:1 triethylsilanol to monomer ratio loading. NMR analysis suggests that the mechanism for syndiotactic induction, in the presence of silyl alcohols, may be similar to that observed with alkyl alcohols. In this case, a 1:2 complex formation, via hydrogen bonding interactions, leads to the induction of syndiotactic specificity.

トルエン中低温でのN-イソプロピルアクリルアミドのラジカル重合系にシリルアルコールを添加すると，シンジオタクチック特異性が誘起されることを見出した．


Effects of chemical composition and stereoregularity on phase-transition behaviors of aqueous solutions of copolymers composed of N-isopropylacrylamide and N-n-propylacrylamide

Radical copolymerizations of N-isopropylacrylamide (NIPAAm) and N-n-propylacrylamide (NNPAAm) in various ratios were carried out in toluene at -40 °C in the presence of 3-methyl-3-pentanol to prepare syndiotactic copolymers with racemo dyad contents of ca. 70%. It was revealed that copolymers containing more than 92.5 mol% NNPAAm units exhibited large phase-transition hysteresis of their aqueous solutions. Sequence analysis suggested that intramolecular hydrogen-bonding of contiguous NNPAAm units in syndiotactic stereosequences in the dehydrated state were responsible for induction of the large hysteresis.

N-イソプロピルアクリルアミドとN-n-プロピルアクリルアミドのラジカル共重合を行い，シンジオタクチックコポリマーを合成した．得られたコポリマーの水溶液の相転移挙動を調べたところ，N-n-プロピルアクリルアミド単位がシンジオタクチックな立体構造で連なると大きなヒステリシスを示すことを見出した．


Control of Stereospecificity in the Radical Polymerization of N-Methyl-N-(2-pyridyl)acrylamide by Conformational Switching of the Monomer with Protonation

Radical polymerization of N-methyl-N-(2-pyridyl)acrylamide (MPyAAm) was carried out in dichloromethane at low temperatures in the presence of trifluoroacetic acid (TFA). The m dyad contents of the polymers obtained at 0 °C increased linearly from 37 to 60% with an increase in the [TFA]0/[MPyAAm]0 ratio from 1 to 5. Nuclear magnetic resonance (NMR) analysis of MPyAAm TFA mixtures in dichloromethane-d2 revealed that the favorable conformation in terms of the pyridyl group to the carbonyl group in MPyAAm switched from s-trans to s-cis by protonation. The results suggest that controlling the conformation of MPyAAm resulted in control of the stereospecificity in radical polymerization of the monomer.

N-Methyl-N-(2-pyridyl)acrylamideのラジカル重合系に酸を添加すると，プロトン化とともにコンホメーションがs-transからs-cisに変化するとともに，重合の立体特異性がシンジオタクチックからイソタクチックに変化することを見出した．


Effect of a combination of hexamethylphosphoramide and alkyl alcohol on the stereospecificity of radical polymerization of N-isopropylacrylamide

Radical polymerization of N-isopropylacrylamide (NIPAAm) was investigated at low temperatures in the presence of both hexamethylphosphoramide (HMPA) and alkyl alcohols. Although HMPA and alkyl alcohols separately induced syndiotactic specificity in NIPAAm polymerization in toluene at low temperatures, a combination of HMPA and less bulky alkyl alcohols, such as methanol and ethanol, was found to induce isotactic specificity at -80 °C. NMR analysis of mixtures of NIPAAm, ethanol and HMPA suggested the formation of a 1:1:1 complex through O H O=C and N H O=P hydrogen bonding. It is believed that the steric effect of HMPA enhanced by cooperative hydrogen bonding was responsible for the combined effect of HMPA and alkyl alcohols in inducing isotactic specificity.

N-イソプロピルアクリルアミドの低温ラジカル重合系にヘキサメチルホスホラミドとアルキルアルコールを同時に添加すると，イソタクチシチーに富むポリマーが得られることを見出した．


Stereospecific Radical Polymerization of N-tert-Butoxycarbonylacrylamide in the Presence of Fluorinated Alcohols

Radical polymerization of N-tert-butoxycarbonylacrylamide (NBocAAm) in toluene at low temperatures in the presence of the fluorinated alcohols, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-propanol, and nonafluoro-tert-butanol, afforded atactic, heterotactic, and syndiotactic polymers, respectively. NMR analysis revealed that the fluorinated alcohols formed hydrogen bonding-assisted complexes with NBocAAm, with different structures. The difference in the structures of the complexes was responsible for the differences in the induced stereospecificities. Based on the structures of the complexes between NBocAAm and the fluorinated alcohols, mechanisms for the three kinds of stereospecific radical polymerizations are proposed.

N-tert-ブトキシカルボニルアクリルアミドのラジカル重合系にフッ素化アルコールを添加すると，添加するアルコールの種類によってアタクチック，ヘテロタクチックおよびシンジオタクチックポリマーが得られることを見出した．NMR解析を行ったところ，それぞれ異なる錯体を形成することが示唆されたことから，水素結合の様式の違いによって異なる錯体を形成したことが異なる立体特異性誘起の要因であることを見出した．


Unusually Large Hysteresis of Temperature-Responsive Poly(N-Ethyl-2-Propionamidoacrylamide) Studied by Microcalorimetry and FT-IR

We reported here the full characterization of the hysteresis of the phase transition behavior of an aqueous solution of poly(N-ethyl-2-propionamidoacrylamide) (PNEPA), which has a unique alpha,alpha-disubstituted structure, by using microcalorimetry and FT-IR. Phase transition temperatures near the thermodynamic equilibrium were determined by extrapolating the scanning rate of the microcalorimetry to zero. The calculated hysteresis from the phase transition temperature was unusually very large (approximately 8 degrees C). FT-IR analysis indicated that the large hysteresis of PNEPA resulted from a coupling of intra-/intermonomeric unit hydrogen bonds, which is known to occur in a beta-sheet of proteins but has never been reported in temperature-responsive polymers. The effects of the molecular weight and polymer concentration on the hysteresis were studied by using fractionated PNEPAs and it was found that a low molecular weight and a low concentration enhanced the hysteresis.


Design of Temperature-Responsive Polymers with Enhanced Hysteresis: α,α-Disubstituted Vinyl Polymers

Three temperature-responsive polymers which are alpha,alpha-disubstituted vinyl polymers having two amphiphilic groups (ethylamide or ethylester) per monomeric unit were designed. Two of these polymers showed unusually large hysteresis in their phase transition temperatures between a heating and a cooling process. This hysteresis resulted from the extremely slow kinetics of the dissolution process of the aggregated polymer chains in the cooling process due to intra- and interchain interactions including hydrogen bonding and hydrophobic interaction. The high density of the amphiphilic substituents on the polymer chain due to the alpha,alpha-disubstituted structure enhanced these intra- and interchain interactions. The large hysteresis was also observed in the volume change of a corresponding hydrogel. These new classes of temperature-responsive polymers are interesting materials because their large hystereses can be regarded as erasable memory function.


The Effect of the N-Substituent s-trans to the Carbonyl Group of N-Methylacrylamide Derivatives on the Stereospecificity of Radical Polymerizations

Radical polymerization of N-methylacrylamide (NMAAm), N,N-dimethylacrylamide (DMAAm), and N-methyl-N-phenylacrylamide (MPhAAm) was investigated in toluene at low temperatures. Atactic, isotactic, and syndiotactic polymers were obtained by the polymerization of NMAAm, DMAAm, and MPhAAm, respectively, indicating that the stereospecificity of the radical polymerization of acrylamide derivatives depended on the N-substituents of the monomer used. From the viewpoint of monomer structure, the origin of the stereospecificity of radical polymerization of NMAAm derivatives is discussed.

N-メチルアクリルアミド誘導体のラジカル重合を行い，カルボニル基に対してトランス位にある置換基が重合の立体特異性決定に重要な役割を果たしていることを見出した．

Journal of Polymer Science Part A: Polymer Chemistry


Multivariate analysis of 13C NMR spectra of methacrylate copolymers and homopolymer blends

13C NMR spectra of copolymers of methyl methacrylate and tert-butyl methacrylate with various chemical compositions, the homopolymers of the two methacrylates, and blends of the homopolymers with various blend ratios were subjected to principal component analysis. The first and second principal components correlated chemical composition and the randomness of comonomer sequence, respectively. Chemical composition of the copolymers was determined with high accuracy and precision by the partial least-squares regression without assignment of individual resonance peaks.

メタクリル酸エステル共重合体の13C NMRスペクトルに多変量解析を適用することで，共重合組成が定量できることを見出した．


Metal-free isotactic-specific radical polymerization of N-alkylacrylamides with 3,5-dimethylpyridine N-oxide: The effect of the N-substituent and solvent on the isotactic specificity

Radical polymerization of N-methylacrylamide (NMAAm), N-n-propylacrylamide, N-isopropylacrylamide (NIPAAm) and N-benzylacrylamide was investigated in CHCl3, CH2Cl2 and CH3CN, in the presence of 3,5-dimethylpyridine N-oxide (35DMPNO) to examine the effects of the N-substituent and the solvent on the isotactic specificity induced by 35DMPNO. With addition of 35DMPNO to radical polymerization of N-alkylacrylamides in CHCl3, isotactic specificity was significantly induced in NIPAAm polymerization but only slightly induced in NMAAm polymerization. Furthermore, mixed solvents of CH3CN and halomethanes such as CHCl3 and CH2Cl2 enhanced the ability of 35DMPNO to induce isotactic specificity, and poly(NIPAAm) with 74% meso dyad was obtained.

3,5-ジメチルピリジンN-オキシド存在下，種々の溶媒中でN-アルキルアクリルアミドのラジカル重合を行い，重合のイソタクチック特異性に及ぼすN-置換基と溶媒の効果について調べた．


Heterotactic-specific radical polymerization of N-isopropylacrylamide and phase transition behavior of aqueous solution of heterotactic poly(N-isopropylacrylamide)

Radical polymerization of N-isopropylacrylamide (NIPAAm) in toluene at low temperatures, in the presence of fluorinated-alcohols, produced heterotactic polymer comprising an alternating sequence of meso and racemo dyads. The heterotacticity reached 70% in triads when polymerization was carried out at -40 °C using nonafluoro-tert-butanol as the added alcohol. NMR analysis revealed that formation of a 1:1 complex of NIPAAm and fluorinated-alcohol through C=O···H O hydrogen bonding induces the heterotactic specificity. A mechanism for the heterotactic-specific polymerization is proposed. Examination of the phase transition behavior of aqueous solutions of heterotactic poly(NIPAAm) revealed that the hysteresis of the phase transition between the heating and cooling cycles depended on the average length of meso dyads in poly(NIPAAm).

N-イソプロピルアクリルアミドのラジカル重合系にフッ素化アルコールを添加すると，ヘテロタクチックポリマーが得られることを見出した．また，ヘテロタクチックポリ(N-イソプロピルアクリルアミド)の水溶液の相転移を調べ，ヒステリシスがメゾ2連子の平均連鎖長に依存することを見出した．


Syndiotactic-specific radical polymerization of N,N-dimethylacrylamide in the presence of tartrates: A proposed mechanism for the polymerization

Radical polymerization of N,N-dimethylacrylamide (DMAAm) was investigated in the presence of tartrates, such as diethyl l-tartrate, diisopropyl l-tartrate, and di-n-butyl l-tartrate, in toluene at low temperatures. Syndiotactic polymers were obtained in the presence of tartrates, whereas isotactic polymers were obtained in the absence of tartrates. The syndiotactic-specificity increased with increasing amount of tartrates and with decreasing polymerization temperature. NMR analysis suggested that DMAAm and tartrates formed a 1:1 complex through double hydrogen bonding. A mechanism for the syndiotactic-specific radical polymerization of DMAAm is proposed.

N,N-ジメチルアクリルアミドのラジカル重合系に酒石酸エステルを添加すると，重合反応を加速するだけでなくシンジオタクチシチシーに富むポリマーを与えることを見出し，反応機構について考察を行なった．


Syndiotactic Poly(N-n-propylacrylamide) Shows Highly Cooperative Phase Transition

Syndiotactic poly(N-n-propylacrylamide)s (PNNPAM) with various racemo (r) diad contents were synthesized, and their phase transition behaviors were studied by high-sensitivity differential scanning calorimetry and FT-IR spectroscopy. The cooperativity of the phase transition increased with the increase in the r diad content. Compared with the atactic PNNPAM, the number of cooperative units, which shows the monomeric units length undergoing cooperative phase transition, increased 2.5- to 4-fold in the syndiotactic polymers. From the results of FT-IR spectroscopy and quantum chemical calculations, it was determined that the high cooperativity of the syndiotactic polymers resulted from local formation of an ordered structure in a dehydrated state.

ポリ(N-n-プロピルアクリルアミド)水溶液の相転移において，シンジオタクチシチーの増加とともに協同性が向上することを見出した．


Radical polymerization behavior of diemthyl vinylphosphonate: homopolymerization and copolymerization with trimethoxyvinylsilane

Dialkyl vinylphosphonates such as dimethyl vinylphosphonate (DMVP) and diethyl vinylphosphonate were quantitatively polymerized with dicumyl peroxide (DCPO) at 130°C in bulk. The polymerization of DMVP with DCPO was kinetically studied in bulk by fourier transform near-infrared spectroscopy (FTNIR) and electron spin resonance (ESR) spectroscopy. The initial polymerization rate (Rp) was given by Rp = k[DCPO]0.5[DMVP]1.0 at 110°C, being the same as that of the conventional radical polymerization involving bimolecular termination. The overall activation energy of the polymerization was estimated to be 26.2 kcal/mol. The polymerization system involved ESR-observable propagating polymer radicals under the practical polymerization conditions. ESR-determined rate constants of propagation (kp) and termination (kt) were kp = 19 L/mol s and kt = 5.8 × 103 L/mol s at 110°C, respectively. The molecular weight of the resultant poly(DMVP)s was low (Mn = 3.4 - 3.5 × 103), because of the high chain transfer constant (Cm = 3.9 × 10-2 at 110°C) to the monomer. DMVP (M1) showed a considerably high reactivity in the radical copolymerization with trimethoxyvinylsilane (TMVS) (M2) at 110°C in bulk, giving an inorganic component-containing functional copolymer with potential flame-retardant properties; r1 = 1.6 and r2 = 0.

リン原子にビニル基が結合したモノマーのラジカル重合を行い，重合速度が通常の二分子停止を含む速度式で表わせることやモノマーへの連鎖移動反応が起こりやすいことなどを見出した．


Molecular Understanding of the UCST-Type Phase Separation Behavior of a Stereocontrolled Poly(N-isopropylacrylamide) in Bis(2-methoxyethyl) Ether

The upper critical solution temperature (UCST)-type phase separation of an isotactic-rich poly(N-isopropylacrylamide) (PNiPA) in bis(2-methoxyethyl) ether (diglyme) has been investigated by turbidity measurement and infrared (IR) spectroscopy. The IR spectra of stereocontrolled PNiPAs in various solvents have clearly indicated that the amide I bands do not directly reflect the tacticity of the polymer. The relative intensity of the amide I bands changes depending upon the molecular environment around the amide groups of PNiPA, which is influenced by the tacticity. During the UCST-type phase separation of the isotactic-rich PNiPA in diglyme, the amide I band at around 1625 cm-1 changes. To link the IR spectral change with the molecular information, quantum chemical calculations have been carried out for NiPA n-mers (n = 1-4) with an isotactic stereosequence. The result has suggested that the amide I band at around 1625 cm-1 arises from a helical structure formed by the isotactic stereosequences in the PNiPA main chain with the aid of intramolecular C O···H-N hydrogen bonding. The experimental IR spectra have revealed that the helical structures are unfolded as the temperature rises. The folding and unfolding of the isotactic sequences in the main chain may induce the thermal change in the solubility of the isotactic rich PNiPA in diglyme, resulting in the UCST-type phase separation of the solution.

イソタクチックポリ(NIPAAm)が有機溶媒中でUCST型の相転移を示すことを見出した．また，IR測定の結果からミクロ構造との関連について考察を行った．


Synthesis of heterotactic and syndiotactic polyacrylamides via stereospecific radical polymerization of N-tert-butoxycarbonylacrylamide in the presence of fluorinated alcohols

Radical polymerization of a new protected monomer, N-tert-butoxycarbonylacrylamide, in toluene at -40 or 0 °C in the presence of fluorinated alcohols was investigated. The obtained polymers were successfully converted into polyacrylamide under acidic conditions. Further, it was revealed that atactic, heterotactic, and syndiotactic polymers were obtained with the addition of trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-propanol, and nonafluoro-tert-butanol, respectively. To the best of our knowledge, these are the first syntheses of heterotactic and syndiotactic polyacrylamides.

N-tert-ブトキシカルボニルアクリルアミドのラジカル重合系にフッ素化アルコールを添加すると，ヘテロタクチックやシンジオタクチックポリマーが得られることを見出した．

Journal of Polymer Science Part A: Polymer Chemistry


Hydrogen-bond-assisted syndiotactic-specific radical polymerizations of N-alkylacrylamides: The effect of the N-substituents on the stereospecificities and unusual large hysteresis in the phase-transition behavior of aqueous solution of syndiotactic poly(N-n-propylacrylamide)

The radical polymerizations of N-alkylacrylamides, such as N-methyl-(NMAAm), N-n-propyl-(NNPAAm), N-benzyl-(NBnAAm), and N-(1-phenylethyl)acrylamides (NPhEAAm), at low temperatures were investigated in the absence or presence of hexamethylphosphoramide (HMPA) and 3-methyl-3-pentanol (3Me3PenOH), which induced the syndiotactic specificities in the radical polymerization of N-isopropylacrylamide (NIPAAm). In the absence of the syndiotactic-specificity inducers, the syndiotacticities of the obtained polymers gradually increased as the bulkiness of the N-substituents increased. Both HMPA and 3Me3PenOH induced the syndiotactic specificities in the NNPAAm polymerizations as well as in the NIPAAm polymerizations. The addition of 3Me3PenOH into the polymerizations of NMAAm significantly induced the syndiotactic specificities, whereas the tacticities of the obtained polymers were hardly affected by adding HMPA. In the polymerizations of bulkier monomers, such as NBnAAm and NPhEAAm, HMPA worked as the syndiotactic specificity inducer at higher temperatures, whereas 3Me3PenOH hardly influenced the stereospecificity. The phase-transition behaviors of the aqueous solutions of poly(NNPAAm)s were also investigated. It appeared that the poly (NNPAAm) with racemo dyad content of 70% exhibited unusual large hysteresis between the heating and cooling processes.

HMPAや3Me3PenOHをN-アルキルアクリルアミドのラジカル重合系に添加し，シンジオタクチックポリマーを合成した．また，シンジオタクチックポリ(N-n-プロピルアクリルアミド)の水溶液が大きなヒステリシスを示すことを見出した．


Hydrogen-Bond-Assisted Syndiotactic-Specific Radical Polymerization of N,N-Dimethylacrylamide in the Presence of Tartrates

The radical polymerizations of N,N-dimethylacrylamide (DMAAm) at low temperatures in the presence of alcohol compounds were investigated. It was found that the addition of tartrates into the DMAAm polymerizations in toluene significantly induced the syndiotactic-specificity. In addition, both the yield and the molecular weights of the obtained polymers increased with the addition of tartrates. To the best of our knowledge, this is the first example of syndiotactic-specific radical polymerization of DMAAm.

N,N-ジメチルアクリルアミドのラジカル重合系に酒石酸エステルを添加すると，重合反応を加速するだけでなくシンジオタクチシチシーに富むポリマーを与えることを見出した．


Hydrogen-bond-assisted syndiotactic-specific radical polymerization of N-isopropylacrylamide: The solvent effect on the stereospecificity

Radical polymerizations of N-isopropylacrylamide (NIPAAm) in several solvents at low temperatures in the absence or presence of hexamethylphosphoramide (HMPA) or 3-methyl-3-pentanol (3Me3PenOH) were examined. The isotacticities of the poly(NIPAAm)s obtained in the absence of HMPA and 3Me3PenOH at lower temperatures slightly increased as the polarities of the solvents used increased. The addition of HMPA significantly induced the syndiotactic-specificity even in polar solvents such as tetrahydrofuran and acetone, although the use of the solvents having proton-donating ability, such as chloroform, prevented the induction of the syndiotactic-specificity, even if their polarities are low. In the presence of 3Me3PenOH, a good correlation between the polarities of the solvents used and the syndiotacticities of the obtained poly(NIPAAm)s was observed, and poly(NIPAAm) with r = 73% was obtained using the toluene/methylcyclohexane mixed solvent.

HMPAまたは3-メチル-3-ペンタノール存在下でのN-イソプロピルアクリルアミドのラジカル重合を種々の溶媒中で行い，溶媒の極性と得られたポリマーの立体規則性との関係について調べた．


Metal-free isotactic-specific radical polymerization of N-isopropylacrylamide with pyridine N-oxide derivatives: The effect of methyl substituents of pyridine N-oxide on the isotactic specificity and the proposed mechanism for the isotactic-specific radical polymerization

The radical polymerizations of N-isopropylacrylamide (NIPAAm) in chloroform at low temperatures in the presence of pyridine N-oxide (PNO) derivatives were investigated. It was found that the methylation at meta-positions of PNO improved the isotactic specificity induced by PNO, whereas the methylation at ortho-positions prevented the induction of the isotactic specificity. NMR analysis revealed that NIPAAm and PNO derivatives formed predominantly 2:1 complex through a hydrogen-bonding interaction. Furthermore, the induction of the isotactic specificity was attributed to the conformationally limited propagating radicals. Based on these findings, the mechanism of the isotactic-specific radical polymerization was discussed.

クロロホルム中でのN-イソプロピルアクリルアミドのラジカル重合におけるピリジンN-オキシド誘導体の添加効果をしらべ，メタ位にメチル基を導入するとイソタクチック特異性が向上することを見出し，反応機構を考察した．


Heterotactic poly(N-isopropylacrylamide) prepared via radical polymerization in the presence of fluorinated alcohols

Radical polymerization of N-isopropylacrylamide in toluene at -40 °C in the presence of fourfold amounts of fluorinated alcohols was investigated. The 13C NMR analysis of the obtained polymers suggested that the addition of fluorinated alcohols induced heterotactic specificity in radical polymerization of NIPAAm, although syndiotactic poly(NIPAAm)s were obtained by adding alkyl alcohols as we have previously reported. To the best of our knowledge, this is the first synthesis of heterotactic poly(NIPAAm).

フッ素化アルコール存在下，N-イソプロピルアクリルアミドのラジカル重合を行うと，ヘテロタクチックポリマーが得られることを見出した．


Initiator-Fragment Incorporation Radical Polymerization of Diallyl Phthalate: Kinetics, Formation of Hyperbranched Polymer, and Iridescent Porous Film Thereof

Diallyl phthalate (DAP) was polymerized in toluene using dimethyl 2,2 -azobisisobutyrate (MAIB) of high concentrations (0.1 0.9 mol/L) as initiator. The polymerization of DAP of 1.50 mol/L with MAIB of 0.50 mol/L proceeded homogeneously at 80°C without gelation to give soluble polymers in a high yield of 93%. Kinetic results of the homogeneous polymerization at 80°C suggest significant contributions of the degradative chain transfer and the primary radical termination as shown by the rate equation, Rp = k [MAIB]0.8[DAP]1.0 (Rp = polymerization rate). The polymer formed in the polymerization of DAP (1.30 mol/L) with MAIB (0.50 mol/L) at 80°C for 8 h consisted of the DAP units with (17 mol %) and without (47 mol %) double bond and the methoxycarbonylpropyl group (36 mol %) as MAIB-fragment. The large fraction of the incorporated initiator-fragment as terminal group indicates that the polymer has a hyperbranched structure. The film cast from a solution of the hyperbranched poly(DAP) in tetrahydrofuran showed an iridescent color. The confocal scanning laser microscope image of the film revealed that the iridescent film contained the pores of about 1 μm arranged in an ordered array.

多量の開始剤(dimethyl 2,2'-azobisisobutyrate)存在下，フタル酸ジアリルのラジカル重合を行うと，有機溶媒に可溶の高分岐ポリマーが得られることを見出した．また，ポリマー溶液のキャストフィルムに規則的な細孔が形成されることも見出した．


Remarkable effect of hydrogen-bonding interaction on stereospecificity in the radical polymerization of N-vinylacetamide

Radical polymerization of N-vinylacetamide (NVA) in toluene at low temperatures was investigated. It was found that the addition of Lewis bases or alcohol compounds significantly influenced stereospecificity in NVA polymerization. For example, syndiotacticity increased from 25% to 34% by adding tri-n-butyl phosphate at -40 °C. Mono-alcohol compounds increased heterotacticity and heterotactic poly(NVA) with mr triad content of 58% was obtained at -40 °C in the presence of 1,1,1,3,3,3-hexafluoro-2-propanol. Furthermore, isotactic poly(NVA) with mm triad = 49% was obtained at -60 °C in the presence of diethyl l-tartrate. The NMR analysis demonstrated that complex formation between NVA monomer and the added agents, through hydrogen-bonding interaction, played an important role to induce the stereospecificity.

N-ビニルアセトアミドのラジカル重合系に，リン酸誘導体，アルコール，フルオロアルコール，酒石酸エステルなどを添加すると，得られるポリマーの立体規則性が制御できることを見出した．


Dual roles of alkyl alcohols as syndiotactic-specificity inducers and accelerators in the radical polymerization of N-isopropylacrylamide and some properties of syndiotactic poly(N-isopropylacrylamide)

The effects of simple alkyl alcohols on the radical polymerization of N-isopropylacrylamide in toluene at low temperatures were investigated. We succeeded in the induction of syndiotactic specificity and the acceleration of polymerization reactions at the same time by adding simple alkyl alcohols such as 3-methyl-3-pentanol (3Me3PenOH) to N-isopropylacrylamide polymerizations. The dyad syndiotacticity increased with a decrease in the temperature and an increase in the bulkiness of the added alcohol and reached up to 71% at -60 °C in the presence of 3Me3PenOH. With the assistance of NMR analysis, it was revealed that the alcohol compounds played dual roles in this polymerization system; an alcohol compound coordinating to the N[BOND]H proton induced syndiotactic specificity, and that hydrogen-bonded to the C[DOUBLE BOND]O oxygen accelerated the polymerization reaction. The effect of syndiotacticity on the properties of poly(N-isopropylacrylamide)s was also examined in some detail.

N-イソプロピルアクリルアミドのラジカル重合系に単純なアルキルアルコールを添加すると，重合反応を加速するだけでなくシンジオタクチシチシーに富むポリマーを与えることを見出した．

Journal of Polymer Science Part A: Polymer Chemistry


Soluble hyperbranched copolymer via initiator-fragment incorporation radical copolymerization using a trivinyl monomer

The initiator-fragment incorporation radical polymerization was extended to a copolymerization system of a trivinyl monomer. The copolymerization of trimethylolpropane trimethacrylate (TMPTM) as a trivinyl monomer with α-methylstyrene (MSt) was examined at 70 and 80 °C in toluene using dimethyl 2,2 -azobisisobutyrate (MAIB) of high concentrations as initiator. When the concentrations of TMPTM, MSt and MAIB were 0.30, 0.60 and 0.50 mol/l, the copolymerization proceeded homogeneously without gelation at 80 °C to yield soluble hyperbranched copolymer in a yield of 65%.

多量の開始剤を用いて3官能性モノマーであるトリビニルモノマーとα-メチルスチレンとのラジカル共重合を行なうと，可溶性の高分岐ポリマーが得られることを見出した．


Synthesis and Characterization of Soluble Hyperbranched Polymer via Initiator-Fragment Incorporation Radical Polymerization of Divinylbenzene with Dimethyl 2,2'-Azobisisobutyrate

The homopolymerization of divinylbenzene (DVB) as an excellent crosslinker (0.20 mol/L) with dimethyl 2,2 -azobisisobutyrate (MAIB) proceeded homogeneously without any gelation at 80°C in benzene when the MAIB concentrations as high as 0.30 0.50 mol/L were used, yielding soluble polymers. In the polymerization at the concentrations of [DVB] = 0.20 mol/L and [MAIB] = 0.50 mol/L, the polymer yield increased with time and leveled off over 90 min. The vinyl groups of DVB were observed to be almost completely consumed in about 80 min, by FT near-IR spectroscopic analysis. The polymer formed in the polymerization for 2 h consisted of 46 mol % of DVB unit and 54 mol % of the methoxycarbonylpropyl group as MAIB fragment, indicating that an initiator-fragment incorporation radical polymerization proceeds in the present polymerization. The polymer was soluble in benzene, tetrahydrofuran, ethyl acetate, chloroform, acetone, and N,N-dimethylformamide, while it was insoluble in n-hexane, acetonitrile, dimethyl sulfoxide, methanol, and water.

多量の開始剤(dimethyl 2,2'-azobisisobutyrate)存在下，ジビニルベンゼンのラジカル重合を行うと，ベンゼン，THF，酢酸エチル，クロロホルム，アセトン，N,N-ジメチルホルムアミドなどの有機溶媒に可溶の高分岐ポリマーが得られることを見出した．


Initiator-fragment incorporation radical copolymerization of vinyl acetate and 1,2-polybutadiene as a multivinyl monomer

The copolymerization of vinyl acetate (VAc) with 1,2-polybutadiene (1,2-PB; 85.5% 1,2-units and 14.5% 1,4-units) as a multivinyl monomer was carried out at 80 °C in dioxane with dimethyl 2,2 -azobisisobutyrate (MAIB) at high concentrations (0.10 0.50 mol/L) as an initiator. The copolymerization of 1,2-PB [0.80 mol/L (monomer unit)] and VAc (1.20 mol/L) with MAIB (0.30 mol/L) for 4 h proceeded homogeneously without gelation to yield a soluble copolymer. The resulting copolymer was divided into methanol- and n-hexane-insoluble parts, of which the yields based on the total weight of the comonomers and initiator were 46 and 20%, respectively. The cast film from a chloroform solution of the methanol-insoluble part contained spherical pores organized in a hexagonal way with a monodisperse pore size of 3 μm. The copolymer molecules seemed to be arranged in an ordered way on the surface layer of the pores, as shown by an optical microscopy image under crossed polarizers.

1,2-ポリブタジエンを多官能性モノマーとして，多量の開始剤を用いて酢酸ビニルとラジカル共重合を行なうと，可溶性ポリマーが得られることを見出した．得られたポリマーをクロロホルム溶液からキャストしてフィルムを作成したところ，3μmの細孔が規則的に並んだ構造を形成することも見出した．


Hyperbranched Polymer through Initiator-Fragment Incorporation Radical Copolymerization of Divinyl Adipate with Allyl Acetate: Synthesis, Characterization, Dye Solubilization, Metal-Nanoparticle Stabilization, and Porous Film Formation

The copolymerization of divinyl adipate (DVA) as an effective cross-linker with allyl acetate (AAc) as a degradative chain transfer reagent was carried out at 70 and 80 °C in benzene using dimethyl 2,2 -azobisisobutyrate (MAIB) of high concentrations as initiator. When the MAIB concentration as high as 0.60 mol/L was used, the copolymerization of DVA (0.20 mol/L) and AAc (0.50 mol/L) proceeded homogeneously without any gelation to give soluble copolymers in a yield of about 30% based on the total weight of DVA, AAc, and MAIB. The copolymer formed in the copolymerization at 80 °C for 6 h consisted of the DVA units with (3 mol %) and without (24 mol %) double bond, the AAc unit (35 mol %), and the methoxycarbonylpropyl group (38 mol %) from MAIB. Such a large fraction of the incorporated initiator-fragment as terminal group indicates that the copolymer has a hyperbranched structure. The copolymer exhibited potentials in solubilization of Rhodamine 6G as a dye probe and stabilization of metal nanoparticles. A porous film was obtained simply by casting a copolymer solution in THF.

多量の開始剤存在下，ジビニルベンゼンとアクリル酸エチルの共重合で得られた可溶性高分岐ポリマーが，色素や銀を包摂して安定化させることや多孔性フィルムを形成することなどを見出した．


Hyperbranched Acrylate Copolymer via Initiator-Fragment Incorporation Radical Copolymerization of Divinylbenzene and Ethyl Acrylate: Synthesis, Characterization, Hydrolysis, Dye-Solubilization, Ag Particle-Stabilization, and Porous Film Formation

Soluble hyperbranched acrylate copolymers were prepared by the copolymerization of divinylbenzene (0.10 mol · L-1) and ethyl acrylate (0.50 mol · L-1) using dimethyl 2,2 -azoisobutyrate of high concentrations (0.30 0.50 mol · L-1) as initiator at 70 and 80 °C in benzene. The copolymer formed at 80 °C for 1 h showed the weight-average molecular weight of 2.5 × 105, the small radius of gyration of 10 nm, the low second virial coefficient of 5.7 × l0-7 mL · g-2 as shown by the MALLS measurements at 25 °C in tetrahydrofuran, and also the very low intrinsic viscosity of 0.10 dL · g-1 at 30 °C in benzene.

Macromolecular Materials and Engineering


Hydrogen-bond-assisted stereocontrol in the radical polymerization of N-isopropylacrylamide with bidentate Lewis base

Radical polymerization of N-isopropylacrylamide (NIPAAm) in toluene was investigated in the presence of bidentate Lewis base such as diphosphonates. Isotacticity of the obtained poly(NIPAAm)s slightly increased at -80 °C, whereas syndiotactic-rich poly(NIPAAm)s were obtained at -40 0 °C. This result corresponded to the results observed in the presence of primary alkyl phosphates. NMR analysis revealed that NIPAAm monomer and tetraisopropyl methylenebisphosphonate formed mono-binding hydrogen-bond-assisted complex at 0 °C, but a chelate complex at -80 °C. Thus, it was concluded that the stereospecificity in NIPAAm polymerization strongly depended on the complexation mode of the added bidentate Lewis base.

トルエン中でのN-イソプロピルアクリルアミドのラジカル重合系にジホスホン酸エステルを添加すると，形成される錯体の構造によって得られるポリマーの立体構造が変化することを見出した．


Radical Polymerization Behavior of Trimethoxyvinylsilane

Trimethoxyvinylsilane (TMVS) was quantitatively polymerized at 130 °C in bulk, using dicumyl peroxide (DCPO) as initiator. The polymerization of TMVS with DCPO was kinetically studied in dioxane by Fourier transform near-infrared spectroscopy. The overall activation energy of the bulk polymerization was estimated to be 112 kJ/mol. The initial polymerization rate (Rp) was expressed by Rp = k[DCPO]0.6[TMVS]1.0 at 120 °C, being closely similar to that of the conventional radical polymerization involving bimolecular termination. The polymerization system involved electron spin resonance (ESR) spectroscopically observable polymer radicals under the actual polymerization conditions. ESR-determined apparent rate constants of propagation and termination were 13 L/mol s and 3.1 × 104 L/mol s at 120 °C, respectively. The molecular weight of the resulting poly(TMVS)s was low (Mn = 2.0 4.4 × 103), because of the high chain transfer constant (Cmtr = 4.2 × 10-2 at 120 °C) to the monomer. The bulk copolymerization of TMVS (M1) and vinyl acetate (M2) at 120 °C gave the following copolymerization parameters: rl = 1.4, r2 = 0.24, Q1 = 0.084, and e1 = +0.80.

これまで重合反応性が低いと考えられてきたトリメトキシビニルシランのラジカル重合が高温では定量的に進行することを見出した．また，速度論的解析から，この重合が2分子停止反応を伴う通常のラジカル重合機構で進行することも見出した．


Hydrogen-bond-assisted isotactic-specific radical polymerization of N-isopropylacrylamide with pyridine N-oxide

Radical polymerization of N-isopropylacrylamide (NIPAAm) in CHCl3 at low temperatures in the presence of pyridine N-oxide (PNO) was investigated. An isotactic poly(NIPAAm) with meso diad content of 61% was successfully prepared at -60 °C in the presence of a two-fold amount of PNO. Thermodynamic analysis suggested that the isotactic-specificity was entropically induced, probably due to conformational fixation near the propagating chain-end through coordination by PNO.

クロロホルム中でのN-イソプロピルアクリルアミドのラジカル重合系にピリジンN-オキシドを添加すると，イソタクチシチーに富むポリマーが得られることを見出した．


Effect of Nitrobenzene on Initiator-Fragment Incorporation Radical Polymerization of Divinylbenzene with Dimethyl 2,2'-Azobisisobutyrate

The polymerization of divinylbenzene (DVB) with dimethyl 2,2 -azobisisobutyrate (MAIB) was conducted at 70 and 80 °C in benzene in the presence of nitrobenzene (NB) as a retarder. When the concentrations of DVB, MAIB, and NB were 0.45, 0.50, and 0.50 mol/l, respectively, the polymerization proceeded without any gelation to yield soluble polymers. The polymer yield (up to 65%) and the molecular weight (Mn=1.5 4.2×l04 at 70 °C and 1.3 3.9×l04 at 80 °C) increased with time. The polymer formed in the polymerization at 80 °C for 4 h consisted of the DVB units with (4 mol%) and without double bond (41 mol%), methoxycarbonylpropyl group as MAIB-fragment (48 mol%), and NB unit (7 mol%). Incorporation of such a large number of the initiator-fragments as terminal groups in a polymer molecule indicates that the polymer is of a hyperbranched structure.

大量の開始剤存在下でのジビニルベンゼンのラジカル重合系にニトロベンゼンを添加すると，抑制剤として働き，可溶性の高分岐ポリマーが得られることを見出した．


Hydrogen-bond-assisted stereocontrol in the radical polymerization of N-isopropylacrylamide with secondary alkyl phosphate: The effect of the bulkiness of the ester group

The addition of triisopropyl phosphate (TiPP) to radical polymerization of N-isopropylacrylamide (NIPAAm) in toluene induced a syndiotactic specificity that was enhanced by the polymerization temperature being lowered, whereas atactic polymers were obtained in the absence of TiPP, regardless of the temperature. Syndiotactic-rich poly(NIPAAm) with a racemo dyad content of 65% was obtained at -60 °C with a fourfold amount of TiPP, but almost atactic poly(NIPAAm)s were obtained by the temperature being lowered to -80 °C. This result contrasted with the result in the presence of primary alkyl phosphates, such as tri-n-propyl phosphate: the stereospecificity varied from syndiotactic to isotactic as the polymerization temperature was lowered. NMR analysis at -80 °C revealed that TiPP predominantly formed a 1:1 complex with NIPAAm, although primary alkyl phosphates preferentially formed a 1:2 complex with NIPAAm. Thus, a slight increase in the bulkiness of the added phosphates influenced the stoichiometry of the NIPAAm phosphate complex at lower temperatures, and consequently a drastic change in the effect on the stereospecificity of NIPAAm polymerization was observed.

N-イソプロピルアクリルアミドのラジカル重合系にリン酸第二級エステルを添加すると，–80℃から0℃でシンジオタクチックリッチポリマーが得られることを見出した．NMR解析から1:1錯体が優先的に生成していることがわかった．リン酸第一級エステルでは–80℃で1:2錯体が優先的に生成することを考えると，かさ高さのわずかな増加が重合の立体特異性に大きな影響を及ぼすことを示している．

Journal of Polymer Science Part A: Polymer Chemistry


Effect of Polymerization Conditions on the Syndiotactic-Specificity in Radical Polymerization of N-isopropylacrylamide and Fractionation of the Obtained Polymer According to the Stereoregularity

Radical polymerization of N-isopropylacrylamide (NIPAAm) was examined in the presence of hexamethylphosphoramide (HMPA). The addition of an excess amount of HMPA induced syndiotactic-specificity that gradually enhanced as the feed monomer was consumed. The syndiotacticity of the obtained poly(NIPAAm)s was improved by increasing the [HMPA]0/[NIPAAm]0 ratio to five and prolonging the polymerization time to 96 h (racemo=72%). It was also revealed that more stereoregulated poly(NIPAAm) could be fractionated by reprecipitating the resulting polymers from hexane THF mixture. This result suggested that more stereoregulated poly(NIPAAm) showed a lower solubility than less stereoregulated poly(NIPAAm)s. Furthermore, unusual hysteresis was observed in transmittance analysis of an aqueous solution of the fractionated syndiotactic poly(NIPAAm).

過剰量のヘキサメチルホスホラミド存在下，トルエン中-60℃でN-イソプロピルアクリルアミドのラジカル重合を行なうと，収率とともにラセモ2連子含量が増加することを見出した．また，再沈殿法によって，立体規則性の高いポリマーを分取することに成功した．さらに，規則性が上がると，溶液物性において，昇温過程および降温過程に著しい差を生じることを見出した．


Kinetic Study of the Radical Polymerization Behavior of N-(1-Phenylethylaminocarbonyl)methacrylamide

Polymerization of N-(1-phenylethylaminocarbonyl)methacrylamide (PEACMA) with dimethyl 2,2 -azobisisobutyrate (MAIB) was kinetically studied in dimethyl sulfoxide (DMSO). The overall activation energy of the polymerization was estimated to be 84 kJ/mol. The initial polymerization rate (Rp) is given by Rp = k[MAIB]0.6[PEACMA]0.9 at 60 °C, being similar to that of the conventional radical polymerization. The polymerization system involved electron spin resonance (ESR) spectroscopically observable propagating poly(PEACMA) radical under the actual polymerization conditions. ESR-determined rate constants of propagation and termination were 140 L/mol s and 3.4 × 104 L/mol s at 60 °C, respectively. The addition of LiCl accelerated the polymerization in N,N-dimethylformamide but did not in DMSO. The copolymerization of PEACMA(M1) and styrene(M2) with MAIB in DMSO at 60 °C gave the following copolymerization parameters; r1 = 0.20, r2 = 0.51, Q1 = 0.59, and e1 = +0.70.

N-(1-phenylethylaminocarbonyl)methacrylamideのラジカル重合の反応速度式および全重合の活性化エネルギーを求めた．また，LiClを加えると重合速度が加速することを見出した．


Direct Synthesis of Syndiotactic-Rich Poly(N-isopropylacrylamide) via Radical Polymerization of Hydrogen-Bond-Complexed Monomer

Radical polymerization of N-isopropylacrylamide (NIPAAm) in toluene was investigated in the presence of hexamethylphosphoramide (HMPA). We succeeded in directly preparing syndiotactic-rich poly(NIPAAm), the syndiotacticity of which (r=70%) is the highest among those of radically-prepared poly(NIPAAm)s so far reported, by lowering polymerization temperature to -60 °C in the presence of a two-fold amount of HMPA. The NMR analysis revealed that the induced syndiotactic-specificity was ascribed to 1:1 complex formation between NIPAAm and HMPA. Furthermore, thermodynamic analysis described that the induced syndiotactic-specificity was enthalpically achieved.

2等量のヘキサメチルホスホラミド存在下，トルエン中-60℃でN-イソプロピルアクリルアミドのラジカル重合を行なうと，ラセモ2連子含量が70%のシンジオタクチックポリマーが得られることを見出した．


Formation of Soluble Hyperbranched Polymer Nanoparticles by Initiator-Fragment Incorporation Radical Polymerization of Ethylene Glycol Dimethacrylate

Ethylene glycol dimethacrylate (1) was polymerized at 70 and 80 °C in benzene using high concentrations of the initiator, dimethyl 2,2 -azobisisobutyrate (2). When the concentrations of 1 and 2 were 0.10 and 0.50 mol · L-1, respectively, the polymerization proceeded homogeneously without any gelation to yield a soluble polymer. The polymerization system involved ESR-detectable polymer radicals in high concentration (3.1 × 10-6 7.5 × 10-6 mol · L-1 at 70 °C). The polymer formed at 80 °C after 4 h consisted of units of 1 with (4 mol-%) and without (38 mol-%) a double bond and a methoxycarbonylpropyl group (58 mol-%) as the fragment of 2. Thus, the initiator-fragment incorporation radical polymerization proceeds in the present polymerization to yield a hyperbranched polymer.

多量の開始剤を用いてエチレングリコールジメタクリレートのラジカル重合を行なうと，可溶性の高分岐ポリマーナノ粒子が得られることを見出した


Initiator-Fragment Incorporation Radical Polymerization of Divinyl Adipate with Dimethyl 2,2'-Azobis(isobutyrate): Kinetics and Formation of Soluble Hyperbranched Polymer

The polymerization of divinyl adipate (DVA) as an effective cross-linker with dimethyl 2,2`-azobis(iosbutyrate) (MAIB) was performed at 70 and 80 °C in benzene. When the MAIB concentrations as high as 0.05-0.50 mol/L were used, the polymerization of DVA (0.30 mol/L) proceeded homogeneously at 80 °C without any gelation to give soluble polymers in the yields of 45-87%. Kinetic investigation on the homogeneous polymerization at 70 °C gave the following rate equation: Rp = k[MAIB]0.3[DVA]1.7 (Rp = initial polymerization rate), indicating a significant contribution of the primary radical termination. The overall activation energy of the polymerization was estimated to be 26.8 kcal/mol. The polymer formed in the polymerization of DVA (0.30 mol/L) with MAIB (0.50 mol/L) at 80 °C for 4 h was composed of the DVA units without (48 mol %) and with (8 mol %) double bond and the methoxycarbonylpropyl group (44 mol %) from MAIB.

多量の開始剤を用いてアジピン酸ジビニルのラジカル重合を行なうと，可溶性の高分岐ポリマーが得られることを見出した ．また，重合速度式および全重合の活性化エネルギーを求めた．


Hydrogen-bond-assisted stereocontrol in the radical polymerization of N-isopropylacrylamide with primary alkyl phosphate: The effect of the chain length of the straight ester group

The radical polymerizations of N-isopropylacrylamide (NIPAAm) were carried out in toluene at low temperatures in the presence of phosphoric acid esters such as trimethyl phosphate, triethyl phosphate (TEP), tri-n-propyl phosphate, and tri-n-butyl phosphate (TBP). Syndiotactically rich poly(NIPAAm)s were obtained from -60 to 0 °C, and TEP provided the highest syndiotacticity (racemo dyad = 65%) at -40 °C. On the other hand, lowering the temperature reversed the stereoselectivity of the propagation reaction so that isotactically rich poly(NIPAAm)s were obtained at -80 °C. In particular, TBP exhibited the most isotactic specificity (meso dyad = 57%). Job's plots for NIPAAm TBP mixtures revealed that NIPAAm and TBP formed a 1:1 complex at 0 °C and a predominantly 1:2 complex at -80 °C through a hydrogen-bonding interaction. Therefore, the stereospecificity of NIPAAm polymerization should depend on the stoichiometry of the hydrogen-bond-assisted complex. Thus, the mechanism for this polymerization system was discussed.

N-イソプロピルアクリルアミドのラジカル重合系にリン酸第一級エステルを添加すると，–40℃ではシンジオタクチックリッチポリマーが得られ，–80℃ではイソタクチックリッチポリマーが得られることを見出した．


Formation of soluble hyperbranched polymer through the initiator-fragment incorporation radical copolymerization of ethylene glycol dimethacrylate with N-methylmethacrylamide

The copolymerization of ethylene glycol dimethacrylate (EGDMA) as a divinyl monomer with N-methylmethacrylamide (NMMAm) as a water-soluble monomer was carried out at 70 and 80 °C in N,N-dimethylformamide (DMF) using dimethyl 2,2 -azobisisobutyrate (MAIB) of high concentrations as initiator. When the concentrations of EGDMA, NMMAm and MAIB were 0.15, 0.50 and 0.35 mol/l, the copolymerization proceeded homogeneously with no gelation at 80 °C to give soluble copolymer in a yield of 50%. EGDMA was polymerized more rapidly than NMMAm as shown by Fourier-transform near infrared spectroscopy. The copolymer formed for 8 h consisted of 20 mol% of EGDMA unit, 47 mol% of NMMA unit and 33 mol% of methoxycarbonylpropyl group unit as MAIB-fragment.

多量の開始剤を用いてエチレングリコールジメタクリレートとN-メチルメタクリルアミドとのラジカル共重合を行なうと，可溶性の高分岐ポリマーが得られることを見出した ．


Radical polymerization of 2-methacryloyloxyethyl phosphorylcholine in water: kinetics and salt effects

The homogeneous polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) as betaine monomer with potassium peroxydisulfate (KPS) was kinetically investigated in water by means of FT-near IR spectroscopy. The overall activation energy of the polymerization was estimated to be 12.8 kcal/mol. The initial polymerization rate (Rp) at 40 °C was given by Rp = k[KPS]0.98[MPC]1.9. The presence of alkaline metal halides accelerated the polymerization. The larger the radius of metal cation or halide ion was, the larger the accelerating effect was. The accelerating salt effect was explained by interactions of salt ions with ionic moieties of the propagating polymer radical and/or the MPC monomer.

ホスホリルコリン残基を有するメタクリル酸エステルのラジカル重合を速度論的に解析し，重合反応速度式を求めた．また，CsClやKClなどの塩を添加すると重合速度は加速されることを見出した．


Reaction control in radical polymerization of di-n-butyl itaconate utilizing a hydrogen-bonding interaction

Radical polymerizations of di-n-butyl itaconate (DBI) were carried out in toluene at 60 °C in the presence of amide compounds. The NMR analysis of DBI and N-ethylacetamide demonstrated both 1:1 complex and 1:2 complex were formed at 60 °C through a hydrogen-bonding interaction. The ESR analysis of radical polymerization of diisopropyl itaconate (DiPI) was conducted in addition to the NMR analysis of the obtained poly(DiPI). It was suggested that the suppression of the intramolecular chain-transfer reaction with the hydrogen-bonding interaction was achieved by controlling the conformation of the side chain at the penultimate monomeric unit of the propagating radical with an isotactic stereosequence.

アミド化合物と水素結合を通して錯形成したイタコン酸エステルのラジカル重合について，錯体の化学量論比，重合系のESRスペクトルおよび生成ポリマー13C NMRスペクトルから反応機構について考察した．

Journal of Polymer Science Part A: Polymer Chemistry


Initiator-fragment incorporation radical polymerization of ethylene glycol dimethacrylate in the presence of 1,1-diphenylethylene: synthesis and characterization of soluble hyperbranched polymer nanoparticles

The polymerization of ethylene glycol dimethacrylate (EGDMA) as crosslinker was carried out at 70 and 80 °C in benzene using dimethyl 2,2 -azobisisobutyrate (MAIB) as initiator at concentrations as high as 0.50 0.70 mol l-1 in the presence of 1,1-diphenylethylene (DPE), where the concentrations of EGDMA and DPE were 0.50 0.70 and 0.25 0.50 mol l-1, respectively. The polymerization proceeded homogeneously, without gelation, to give soluble polymers. The yield and molecular weight of the resulting polymers increased with time.

ジフェニルエチレン存在下，多量の開始剤を用いてエチレングリコールジメタクリレートのラジカル重合を行なうと，可溶性の高分岐ポリマーナノ粒子が得られることを見出した．


Radical polymerization behavior of vinyl phenylsufonylacetate

Vinyl phenylsulfonylacetate (VPSA) was prepared by the reaction of vinyl chloroacetate with sodium benzenesulfinate in acetone in the presence of a phase-transfer catalyst. VPSA showed a high radical homopolymerizability similar to vinyl acetate in spite of the fact that VPSA carries a phenyl group. The polymerization of VPSA with 2,2 -azobisisobutyrate (MAIB) was kinetically investigated in acetone. The overall activation energy of the polymerization was 27.6 kcal/mol. The polymerization rate (Rp) at 50 °C was expressed by Rp=k[MAIB]0.67[VPSA]1.1. Poly(VPSA) showed exothermic (27 °C) and endothermic (57 °C) peaks in its DCS curve, corresponding to crystallization and melting. The tacticity of poly(VPSA) was estimated to be rr=29, mr=49, and mm=22.

vinyl phenylsulfonylacetateを合成し，そのラジカル重合を速度論的に調べた．また生成ポリマーが高い結晶性を有することを見出した．


Significant effect of hydrogen-bonding interaction on syndiotactic-specificity in radical polymerization of N-isopropylacrylamide

Radical polymerization of N-isopropylacrylamide (NIPAAm) was investigated in toluene at 0 °C in the presence of Lewis base. It was found that O-coordinating Lewis base enhanced syndiotactic-specificity of NIPAAm polymerization and, in particular, the syndiotactic diad reached up to 63% in the presence of twofold amount of hexamethylphosphoramide (HMPA). This is the first example of a direct synthesis of a syndiotactic-rich poly(NIPAAm) by a radical polymerization. The NMR analysis revealed that the 1:1 complex formation of NIPAAm and HMPA through a hydrogen-bonding interaction is the key of the syndiotactic-specific radical polymerization. The mechanism for the present polymerization system was discussed.

N-イソプロピルアクリルアミドのラジカル重合系に酸素で配位するルイス塩基を添加すると，シンジオタクチック特異性が向上することを見出した．


Kinetic study of the crosslinking reaction of 1,2-polybutadiene with dicumyl peroxide in the absence and presence of vinyl acetate

The crosslinking reaction of 1,2-polybutadiene (1,2-PB) with dicumyl peroxide (DCPO) in dioxane was kinetically studied by means of Fourier transform near-infrared spectroscopy (FTNIR). The crosslinking reaction was followed in situ by the monitoring of the disappearance of the pendant vinyl group of 1,2-PB with FTNIR. The initial disappearance rate (R0) of the vinyl group was expressed by R0 = k[DCPO]0.8[vinyl group]-0.2 (120 °C). The overall activation energy of the reaction was estimated to be 38.3 kcal/mol. The unusual rate equation was explained in terms of the polymerization of the pendant vinyl group as an allyl monomer involving degradative chain transfer to the monomer.

酢酸ビニル存在下での1,2-ポリブタジエンの架橋反応を近赤外分光法およびESR分光法を用いて速度論的に調べ，架橋反応の速度式を求めた．


Formation of a soluble hyperbranched polymer via initiator-fragment incorporation radical copolymerization of divinyl adipate and isobutyl vinyl ether

The copolymerization of divinyl adipate (DVA) with isobutyl vinyl ether (IBVE) was conducted at 70 and 80 °C in benzene using azobisisobutyronitrile (AIBN), at a concentration as high as 0.50 mol l-1 as the initiator, where the concentrations of DVA and IBVE were 0.40 and 0.60 mol l-1, respectively. The copolymerization proceeded homogeneously, without any gelation, to yield soluble copolymers in spite of the high molar ratio of DVA as an excellent cross-linker for IBVE.

多量の開始剤を用いてアジピン酸ジビニルとイソブチルビニルエーテルとのラジカル共重合を行なうと，可溶性の高分岐ポリマーが得られることを見出した


Initiator-fragment incorporation radical copolymerization of divinylbenzene and N-isopropylacrylamide with dimethyl 2,2'-azobisisobutyrate: Formation of soluble hyperbranched polymer nanoparticle

The copolymerization of divinylbenzene (DVB) and N-isopropylacrylamide (NIPAm) with dimethyl 2,2 -azobisisobutyrate of a concentration as high as 0.50 mol/L proceeded homogeneously without any gelation at 80 °C in N,N-dimethylformamide, where the concentrations of DVB and NIPAm were 0.15 and 0.50 mol/L. The copolymer yield increased with time and leveled off over 50 min. Although DVB was consumed more rapidly than NIPAm, both comonomers were completely consumed in 50 min.

多量の開始剤を用いてジビニルベンゼンとN-イソプロピルアクリルアミドとのラジカル共重合を行なうと，可溶性の高分岐ポリマーナノ粒子が得られることを見出した


Devulcanization of nitrile butadiene rubber in nitrobenzene

Sulfur-crosslinked nitrile butadiene rubber (s-NBR) was found to be devulcanized when it was heated with nitrobenzene at 200°C for 3 h. The tetrahydrofuran (THF)-soluble fraction from s-NBR heated with nitrobenzene was purified by reprecipitation with THF/n-hexane, chloroform/n-hexane, and THF/n-hexane systems and was then characterized by means of Fourier transform infrared (FTIR) spectroscopy, 1H-NMR, gel permeation chromatography, dynamic thermogravimetry/differential thermal analysis (DTA), and differential scanning calorimetry (DSC).

加硫されたニトリルブタジエンゴムをニトロベンゼン中高温で処理すると，脱硫して可溶性高分子を与えることを見出した．


Soluble hyperbranched polymer through initiator-fragment incorporation radical copolymerization of ethylene glycol dimethacrylate and α-ethyl β-N-(α'-methylbenzyl) itaconamate in benzene

The copolymerizations of ethylene glycol dimethacrylate (EGDM) with α-ethyl β-N-(α -methylbenzyl) itaconamates (RS- and S-EMBIs) derived from (RS)- and (S)-α-methylbenzylamines were conducted at 70 and 80 °C in benzene using dimethyl 2,2 -azobisisobutyrate (MAIB) of high concentration as initiator. The copolymerization of EGBM (0.20 mol/l) and RS-EMBI (0.50 mol/l) with MAIB (0.50 mol/l) proceeded homogeneously without any gelation in benzene to give benzene-soluble copolymer in a yield of 55% based on the total weight of EGDM, RS-EMBI and MAIB.

多量の開始剤を用いてエチレングリコールジメタクリレートとイタコナメート誘導体とのラジカル共重合を行なうと，可溶性の高分岐ポリマーが得られることを見出した．


Effect of Hydrogen-Bonding Interaction on Radical Polymerization of Di-n-butyl Itaconate

Radical polymerizations of di-n-butyl itaconate (DBI) were carried out in toluene at 60 °C in the presence of amide compounds. The 13C-NMR spectra of the obtained poly(DBI)s indicated that the intramolecular chain-transfer reaction was suppressed as compared with in the absence of amide compounds.

アミド化合物と水素結合を通して錯形成したイタコン酸ジ-n-ブチルのラジカル重合を行うと，副反応として起こる分子内連鎖移動反応をある程度抑制することができることを見出した．

Journal of Polymer Science Part A: Polymer Chemistry


Radical Polymerization Behavior of 3-(N-2-Methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate in Water

Kinetic study for radical polymerization of betaine monomer, 3-(N-2-Methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate, was carried out in water. The rate equation was determined. Furthermore, the polymerization was accelerated with addition of salts, such as CsCl and KCl.

ベタイン構造を有するメタクリル酸エステルのラジカル重合を速度論的に解析し，重合反応速度式を求めた．また，系にCsClやKClなどの塩を添加すると，重合速度が加速することを見出した．


Initiator-Fragment Incorporation Radical Polymerization of Divinylbenzene in the Presence of Glyoxylic Oxime Ether: Formation of Soluble Hyperbranched Polymer

Soluble hyperbranched polymers were successfully prepared from radical polymerization of divinylbenzene in the presence of glyoxylic wxime ether, which is a retarder for styrene polymerization, with a large amount of radical initiators.

スチレンのラジカル重合の抑制剤であるグリオキシリックオキシムエーテル存在下，多量の開始剤を用いてジビニルベンゼンのラジカル重合を行なうと，可溶性の高分岐ポリマーが得られることを見出した．


Radical Polymerization of Di-n-butyl Itaconate in the Presence of Lewis Acids

Radical polymerization of di-n-butyl itaconate was investigated in the presence of Lewis acids such as Sc(OTf)3. Side reaction, intramolecular chain transfer reaction, was partially suppressed taking advantage of complex formation between the monomer and Lewis acids.

Sc(OTf)3などのルイス酸と錯形成したイタコン酸ジ-n-ブチルのラジカル重合を行うと，副反応として起こる分子内連鎖移動反応をある程度抑制することができることを見出した．


Fourier transform near-infrared and electron spin resonance studies on the crosslinking reaction of liquid carboxylated poly(acrylonitrile-co-butadiene) rubber with dicumyl peroxide in dioxane

Cross-linking reaction of acrylonitrile-butadiene copolymers was investigated with the aid of near infrared and ESR spectroscopies. Rate equation for the cross-linking reaction was determined.

アクリロニトリル/ブタジエン共重合体の架橋反応を近赤外分光法およびESR分光法を用いて解析し，架橋反応の速度式を求めた．


Elementary Reaction Analysis of the Radical Polymerization of α-Ethyl β-N-(α'-Methylbenzyl)itaconamates Carrying (RS)- and (S)-α-Methylbenzylaminocarbonyl Groups

α-Ethyl β-N-(α'-Methylbenzyl)itaconamates carrying (RS)- and (S)-α-nethylbenzylaminocarbonyl groups were prepared from racemic and S-α-methylbenzylamines. Kinetic study of radical polymerization of the monomers revealed that polymerization proceeded rapidly in benzene compared with in methanol. Furthermore, the racemic monomer was consumed faster than optically active monomer.

ラセミまたはS-α-メチルベンジルアミンから合成したイタコナミド誘導体のラジカル重合を速度論的に研究し，メタノール中よりもベンゼン中の方が，また光学活性モノマーよりもラセミ体モノマーの方が速く重合することを見出した．


13C NMR and electron spin resonance analyses of the radical polymerization of diisopropyl itaconate

ESR analysis for radical polymerization of diisopropyl itaconate was performed. Two kinds of signals were observed. These signals were assigned to the propagating radicals with different conformations. 13C NMR analysis of the polymers obtained suggested the relationship between the conformation and stereochemistry near the propagating chain end.

イタコン酸ジイソプロピルのラジカル重合のESR測定と得られたポリマーの13C NMR測定を行い，ESRスペクトル中で観測された2種類のコンホメーションの異なるラジカルと末端近傍の立体規則性との関係を明らかにした．


Effect of Glyoxylic Oxime Ether on Radical Polymerization of Styrene

Radical polymerization of styrene and vinyl acetate was investigated in the presence of glyoxylic oxime ether. It was found that glyoxylic oxime ether behaved as a retarder in the styrene polymerization and an inhibitor in the vinyl acetate polymerization.

グリオキシリックオキシムエーテルがスチレンのラジカル重合の抑制剤，酢酸ビニルのラジカル重合の禁止剤となることを見出した．


Chain-transfer reaction in the radical polymerization of di-n-butyl itaconate at high temperatures

13C NMR analysis of radically prepared poly(di-n-butyl itaconate)s was carried out. It was found that intramolecular chain-transfer reaction occurred over 60°C. Furthermore, the racemo-ended radical favorably took place the intramolecular chain-transfer reaction more then the meso-ended radical.

ラジカル重合で得られたポリ(イタコン酸ジ-n-ブチル)の13C NMR解析を行い，60℃よりも高温では分子内連鎖移動反応が起こっていることおよびラセモ末端ラジカルの方が分子内連鎖移動反応を起こしやすいことを見出した．

Journal of Polymer Science Part A: Polymer Chemistry


Radical and cationic polymerizations of 2-(N,N-dimethyldithiocarbamoyl)ethyl vinyl ether and use of the resulting polymers as photoinitiator

2-(N,N-Dimethyldithiocarbamoyl)ethyl vinyl ether was prepared and polymerization behavior of this monomer was investigated. Radical and cationic polymerization provided polymers with different polymer backbone. In addition, the polymers obtained were found to behave as photo-initiators.

2-(N,N-dimethyldithiocarbamoyl)ethyl vinyl etherを合成し，ラジカル重合およびカチオン重合を行なった．異なる重合法を選択することで，主鎖骨格の異なるポリマーを合成できること，またこれらのポリマーが有効な光開始剤となることを見出した．


Radical polymerization of vinyl thiocyanatoacetate:Participation of group-transfer mechanism

Vinyl thiocyanatoacetate was prepared and polymerization behavior of this monomer was investigated. It was found that polymerization reaction proceeded not only via vinyl mechanism but also cyano-group transfer mechanism, resulting in polyester-polythioether backbone polymers.

vinyl thiocyanatoacetateを合成し，そのラジカル重合挙動を調べた．ビニル重合だけでなく，シアノ基が移動するグループ移動機構でも重合が進行し，polyester-polythioether骨格のポリマーを与えることを見出した．


Vinyl Polymerization with a Binary System of p-Chlorobenzenediazonium Salt and Sodium Tetraphenylborate

Combination of sodium tetraphenylborate and p-chlorobenzendiazonium tetrafluoroborate was found to be low temperature radical initiator for acrylic monomers.


Polymerization of vinyl acetate initiated with di-tert-butyl perfumarate

Radical copolymerization of vinyl acetate and di-tert-butyl perfumarate, which is bifunctional radical initiator, gave only polymers with low molecular weights. However, the polymers obtained behaved macroinitiator for radical polymerization of vinyl acetate, resulting in formation of high molecular weight polymers.

二官能性開始剤でもあるdi-tert-butyl perfumarateと酢酸ビニルとの共重合を行なうと低分子量のポリマーしか得られないが，この低分子量ポリマーをマクロ開始剤として酢酸ビニルの重合を行なうと高分子量ポリマーが得られることを見出した．


Radical Heterogeneous Polymerization Behavior of N-Methyl-α-Fluoroacrylamide in Benzene

Kinetic study for radical polymerization of N-methyl-α-fluoroacrylamide was carried out. ESR analysis revealed that radical concentration increased with time, because long-lived radical formed because of heterogeneous situation.

N-メチル-α-フルオロアクリルアミドのラジカル重合を速度論的に解析し，系が不均一化するとともに，取り残されて長寿命化されたラジカル濃度が増加することをESRを用いて確認した．


Kinetic and ESR Studies of Ring-Opening Radical Polymerization of 1,1-Bis(ethoxycarbonyl)-2-vinylcyclopropane

Kinetic study for ring-opening radical polymerization of 1,1-bis(ethoxycarbonyl)-2-vinylcyclopropane was performed. It was found that the polymerization obeys the rate equation proposed for conventional vinyl polymerization.

1,1-ビス(エトキシカルボニル)-2-ビニルシクロプロパンの開環ラジカル重合を速度論的に解析し，従来のビニル重合と同様の速度式に従うことを見出した．


Radical and cationic polymerization of 3-ethyl-3-methacryloyloxymethyloxetane

Methacrylate monomer having cationically-polymerizable oxetane side group was prepared. Radical initiator gave vinyl polymers, whereas cationic initiator produced polyether.

カチオン重合性官能基であるオキセタンを側鎖にもつメタクリル酸エステルモノマーを合成し，ラジカル重合系開始剤またはカチオン重合系開始剤を使い分かることで主鎖骨格のことなるポリマーを合成した．


Kinetic and ESR Studies on Radical Polymerization Behavior of N-(2-Phenylethoxycarbonyl)methacrylamide

Over-all activation energy and rate equation for radical polymerization of N-(2-phenylethoxycarbonyl)methacrylamide were kinetically determined. Furthermore, annealing converted the corresponding polymers into poly(methacrylamide)s with removing styrene and CO2 molecules.

N-(2-フェニルエトキシカルボニル)メタクリルアミドのラジカル重合を速度論的に研究し，全重合の活性化エネルギーや反応速度式を求めた．また熱分解させると，スチレンおよび二酸化炭素の脱離とともにポリメタクリルアミドへと誘導できることも見出した．

Journal of Polymer Science Part A: Polymer Chemistry


Kinetic and ESR studies on the radical polymerization of α-N-(α'-methylbenzyl) β-ethyl itaconamates derived from racemic and (S)-α-methylbenzylamines

Methacrylamide derivatives were prepared from racemic and S-α-methylbenzylamines. Kinetic study of radical polymerization of the monomers revealed that the racemic monomer was consumed faster than optically active monomer.

ラセミまたはS-α-メチルベンジルアミンから合成したメタクリルアミド誘導体のラジカル重合を速度論的に研究し，ラセミ体モノマーの方が光学活性モノマーよりも速く重合することを見出した．

Journal of Polymer Science Part A: Polymer Chemistry


Living Ring-Opening Polymerization of ε-Caprolactone with Combinations of tert-Butyllithium and Bulky Aluminum Phenoxides

Anionic ring-opening polymerization of ε-caprolactone with t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminum was found to be high-speed living polymerization, in which the monomer was completely consumed within 1 min.

t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminumを開始剤とし，ε-カプロラクトンの開環重合を行うと，1分以内に重合が完了する高速リビングアニオン重合となることを見出した．


13C NMR Analysis of Uniform Heterotactic Oligo(allyl methacrylate) Aiming at Understanding Even-Odd Alternation in Distribution of Degree of Polymerization

Anionic oligomerization of allyl methacrylate with t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminum was carried out to obtain heterotactic oligomer. Uniform oligomers were fractionated by supercritical fluid chromatography. 13C NMR revealed that the structure of the oligomers with odd number DPs were better defined than those with even number DPs.

t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminumを開始剤とするメタクリル酸アリルのヘテロタクチックオリゴマー化反応で得られたオリゴマーを超臨界流体クロマトグラフィーで重合度別に分取し，優先的に生成した奇数重合度オリゴマーの方が開始末端から停止末端までより規制された構造を有することを見出した．


Temperature dependence of stereospecificity in the radical polymerization of di-n-butyl itaconate in bulk

Radical bulk polymerization of di-n-butyl itaconate was carried out at a wide range of temperatures from 78°C to 120°C. 13C NMR analysis revealed that syndiotacticity increased with decrease in the polymerization temperature.

イタコン酸ジ-n-ブチルのラジカルバルク重合を–78℃∼120℃で行った．13C NMRで立体規則性を調べたところ，温度の低下とともにシンジオタクチシチーが増加することを見出した．


Unusual Distribution of Degree of Polymerization Observed for Heterotactic Oligomer of Allyl Methacrylate

Anionic oligomerization of allyl methacrylate with t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminum was carried out to obtain heterotactic oligomer. Supercritical fluid chromatography revealed that the oligomers with odd number degrees of polymerization (DP) were preferentially formed more than those with even number DPs.

t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminumを開始剤とするメタクリル酸アリルのヘテロタクチックオリゴマー化反応で得られたオリゴマーの重合度分布を超臨界流体クロマトグラフィーを用いて解析し，奇数重合度オリゴマーの方が優先的に生成していることを見出した．


Discrimination of Poly(ethyl methacrylate)s According to Their Molar Mass and Tacticity by Coupling Size Exclusion Chromatography and Liquid Chromatography at Critical Adsorption Point

Isotactic, syndiotactic and heterotactic poly(ethyl methacrylate)s with the same chemical structure from the initiating to terminating chain-ends were prepared by anionic polymerizations. It was found that HPLC under the critical adsorption point successfully separates the polymers by stereoregularities, instead of molecular weights.

開始末端から停止末端まで同じ化学構造を有する3種類(イソタクチック，シンジオタクチックおよびヘテロタクチック)のポリ(メタクリル酸エチル)のHPLC測定において，吸着機構とサイズ排除機構がつり合う溶離液を用いることで，分子量ではなく立体規則性で分離できることを見出した．


Heterotactic Polymerization of Methacrylates Having C-3 Ester Group

Anionic polymerization of allyl methacrylate with t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminum gave heterotactic polymer with mr triad of 96%. The 96% mr triad was the highest heterotacticity among the heterotactic polymers reported so far.

t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminumを開始剤として，メタクリル酸アリルのアニオン重合を行うと，ヘテロタクチック3連子含量が96%のこれまでで最も規則性の高いヘテロタクチックポリマーが得られることを見出した．


Effect of Ester Compounds on Stereospecificity in Methacrylate Polymerization with t-BuLi/Bis(2,6-di-t-butylphenoxy)methylaluminum

種々のエステル化合物存在下，t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminumを開始剤とするメタクリル酸エチルのヘテロタクチックアニオン重合を行い，エステルの添加によってラセモ末端アニオンのヘテロタクチック選択性が低下し，メゾ末端アニオンのヘテロタクチック選択性が向上することを見出した．


Remarkable Effect of Structure of Bulky Aluminum Phenoxides on Stereospecificity of Methacrylate Polymerization

Anionic polymerization of ethyl methacrylate was carried out with t-BuLi / bis(2,6-di-t-butylphenoxy)alkylaluminum. It was found that the alkyl group bound to the aluminum center influenced the stereospecificity; methyl group induced heterotactic specificity and ethyl group induced syndiotactic specificity.

t-BuLi とalkylaluminum bis(2,6-di-t-butylphenoxide)の組み合わせからなる開始剤を用いてメタクリル酸エチルのリビングアニオン重合を行い，アルキル基がメチル基の時にはヘテロタクチックポリマーが，エチル基の時にはシンジオタクチックポリマーが得られることを見出した．


Remarkable Change of Stereochemistry near the Terminating Chain-End of Heterotactic Poly(ethyl methacrylate) with Conversion. Importance in Mechanistic Study of Stereospecific Polymerization with the Aid of Chain-End Analysis

Anionic polymerization of ethyl methacrylate was carried out with t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminum to obtain heterotactic polymers. Tacticity distribution was found to vary with time even after the monomer was fully consumed. The structure of the propagating anions was discussed.

t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminumを開始剤とするメタクリル酸エチルのヘテロタクチックアニオン重合で得られたポリマーの停止末端近傍の立体規則性分布が反応終了後，時間とともに変化することを見出し，成長アニオンの構造に関する知見を得た．


Highly Heterotactic Polymerization of Methacrylates - Higher Order Stereoregulation and Stereochemical Significance

Anionic polymerization of ethyl methacrylate was carried out with t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminum to obtain heterotactic polymers. Mechanism of the heterotactic-specific polymerization was discussed based on tacticity distribution near the chain ends and in chain, which were characterized by 13C NMR.

t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminumを開始剤とするメタクリル酸エチルのヘテロタクチックアニオン重合を行い，その末端近傍および主鎖の立体規則性分布を13C NMRを用いて調べ，ヘテロタクチック重合の反応機構について考察した．


Chain-End Stereostructure of Heterotactic Poly(ethyl methacrylate) Prepared with t-Butyllithium/Bis(2,6-di-t-butylphenoxy)methylaluminum as Studies by 13C NMR Spectroscopy

Anionic polymerization of ethyl methacrylate was carried out with t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminum to obtain heterotactic polymers. 13C NMR analysis of tacticity distribution near the chain ends revealed stereoselectivity in the initiating reaction and effect of stereochemistry at the second diad from the chain end on stability of the propagating anion.

t-BuLi / bis(2,6-di-t-butylphenoxy)methylaluminumを開始剤とするメタクリル酸エチルのヘテロタクチックアニオン重合を行い，その末端近傍の立体規則性分布を13C NMRを用いて調べることで，開始反応の立体選択性および成長アニオンの安定性に関する知見を得た．