Preparation of Truly Random Copolymers of Homogenous Composition by Equilibrium Ring-opening Copolymerization

平衡开环共聚制备均质真无规共聚物

• 批准号: 15550106
• 负责人: MIYAMOTO Masatoshi
• 金额: $ 2.37万
• 依托单位: Kyoto Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15550106/
• 关键词: equilibrated ring-opening copolymerization; homogeneous copolymer; ε-caprolactone; γ-butyrolactone; tetrahydrofuran; enzymatic degradation; biodegradability; ランダム共重合; ポリグリコール酸; グリコリド; テトラメチルグリコリド; 均一組成ランダム共重合体; THF; アニオン共重合; カチオン共重合

Random copolymerization is often carried out to improve or modify properties of homopolymers. In random copolymerization to prepare a commercial material, it is very important to keep the copolymer's composition constant as the variation in the composition often degrades the optical, thermal, and mechanical properties of material. However, it is difficult to prepare random copolymer of homogeneous composition by ring-opening copolymerization.A new concept in ring-opening copolymerization that a truly statistic copolyester is readily obtained by the copolymerization with a non-polymerizable comonomer, e.g.γ-butyrolactone (BL), was postulated under the name of "equilibrated ring-opening copolymerization (ERC)", and its appropriateness was proven theoretically. The validity of the concept was demonstrated for the anionic copolymerization between ε-caprolactone (CL) and BL, which gave copolymers of uniform composition containing <8 mol% of the BL units. Contrary to the conventional copolym … More erization, the copolymer's composition was hardly changed throughout the copolymerization, although the ratio between the remaining monomers was drastically changed according to the progress of copolymerization. This copolymerization technique could be successfully applied to the copolymerization between glycolide (GL)/BL and CL/THF systems, the latter was examined with methyl trifluoromethanesulfonate, a cationic initiator : the comonomer's content reached to 3% in the former case and 50% in the latter combination with increasing the comonomer's initial concentration.The effect of homogeneity on the thermal and biodegradable natures of poly(CL-co-BL) was further investigated. Copolymers of tapered composition were prepared by the sequential addition of BL into the copolymerization systems for reference. Homogeneous copolymer generally shows lower T_m than the heterogeneous copolymer having analogous BL content, while T_g was not influenced by the homogeneity. On the other hand, the crystallinity of heterogeneous copolymer was slightly higher than that of homogeneous copolymer. The homogeneous copolymer was biodegraded more readily than the corresponding heterogeneous copolymer. Less

通常进行无规共聚以改善或改变均聚物的性能。在无规共聚制备商业材料时，保持共聚物的组成恒定非常重要，因为组成的变化通常会降低材料的光学、热和机械性能。然而，通过开环共聚很难制备均匀组成的无规共聚物。开环共聚中的一个新概念被提出，即“平衡开环共聚（ERC）”，即通过与不可聚合的共聚单体，例如γ-丁内酯（BL）共聚，很容易获得真正统计的共聚酯。 从理论上证明了其合理性。 ε-己内酯 (CL) 和 BL 之间的阴离子共聚证明了这一概念的有效性，得到了含有 <8 mol% BL 单元的均匀组成的共聚物。与传统的共聚相反，尽管剩余单体之间的比例根据共聚的进展发生了巨大的变化，但在整个共聚过程中，共聚物的组成几乎没有变化。该共聚技术可成功应用于乙交酯(GL)/BL和CL/THF体系之间的共聚，后者用阳离子引发剂三氟甲磺酸甲酯进行了测试：随着共聚单体初始浓度的增加，前者的共聚单体含量达到3%，后者的共聚单体含量达到50%。 进一步研究了聚（CL-co-BL）的生物降解性质。通过将BL依次添加到共聚体系中制备了递变组成的共聚物以供参考。均质共聚物通常表现出比具有类似BL含量的非均质共聚物更低的T_m，而T_g不受均质性的影响。另一方面，非均相共聚物的结晶度略高于均相共聚物。均相共聚物比相应的非均相共聚物更容易生物降解。较少的