label: url

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

en: Molecular Catalysis

ja: Molecular Catalysis


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

en: Polymer

ja: Polymer


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

en: 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.

ja: 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．

en: European Polymer Journal

ja: European Polymer Journal


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

en: Organic & Biomolecular Chemistry

ja: Organic & Biomolecular Chemistry


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

en: 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.

ja: 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．


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

en: 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．


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

en: 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．

en: Journal of Polymer Science

ja: Journal of Polymer Science


en: Chemoselective transesterification and polymer synthesis using a zincate complex

en: 亜鉛アート錯体TBZLを用いた化学選択的なエステル交換反応およびポリマー合成について報告した．

en: Polymer Journal

ja: Polymer Journal


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

en: 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．


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

en: 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．

en: Polymer


en: NMR Analysis of Poly(Lactic Acid) via Statistical Models

en: 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.

en: Polymers

ja: Polymers


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

ja: 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

en: The Review of High Pressure Science and Technology

ja: 高圧力の科学と技術


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

en: 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．

en: Polymer Chemistry

ja: Polymer Chemistry


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

en: 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.

ja: 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．


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

en: Tetrahedron Letters

ja: Tetrahedron Letters


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

en: 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．


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

en: 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.

ja: 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．


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

en: Polymer Journal


en: 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

en: 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.

ja: 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．

en: RSC Advances

ja: RSC Advances


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

en: 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.

ja: 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．

en: Polymer


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

en: 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.

ja: 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．

ja: Polymer


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

en: 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.

ja: 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．


en: 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)

en: 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).

ja: 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．

en: Journal of Polymer Science Part A: Polymer Chemistry


en: Synthesis of Periodic Copolymers via Ring-Opening Copolymerizations of Cyclic Anhydrides with Tetrahydrofuran Using Nonafluorobutanesulfonimide as an Organic Catalyst and Subsequent Transformation to Aliphatic Polyesters

ja: Journal of Polymer Science Part A: Polymer Chemistry


en: Ring-Opening Polymerization of ϵ-Caprolactone Catalyzed by Rare-Earth Lewis Acid or Perfluoroalkanesulfonimides

ja: 希土類ルイス酸またはパーフルオロアルカンスルホンイミドを触媒に用いたϵ-カプロラクトンの開環重合

en: Japanese Journal of Polymer Science and Technology

ja: 高分子論文集


en: Ring-Opening Polymerization of ε-Caprolactone Using Perfluoroalkanesulfonates and Perfluoroalkanesulfonimides as Organic Catalysts


en: Controlled Ring-Opening Polymerization of ε-Caprolactone Catalyzed by Rare-Earth Perfluoroalkanesulfonates and Perfluoroalkanesulfonimides

en: Macromolecules

ja: Macromolecules


en: Controlled Ring-Opening Polymerization of ε-Caprolactone Using Polymer-Supported Scandium Trifluoromethanesulfonate in Organic Solvent and Ionic Liquids


en: Dual Catalytic System for Combination of Chain and Step Polymerizations: Ring-Opening Polymerization of ϵ-Caprolactone and Successive Dehydration Polycondensation with Dicarboxylic Acid Using the Same Catalyst


en: Controlled Ring-Opening Polymerization of ε-Caprolactone Using Polymer-Supported Scandium Catalyst