Lewis酸碱对催化的可再生环状缩醛酯单体的开环聚合研究  

Lewis Pair-catalyzed Ring-opening Polymerization of Renewable Cyclic Acetal Ester Monomers

作　　者：汤家栋 李茂盛[1] 陶友华[1,2] Jia-dong Tang;Mao-sheng Li;You-hua Tao(Key Laboratory of Polymer Ecomaterials,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Changchun 130022;School of Applied Chemistry and Engineering,University of Science and Technology of China,Hefei 230026)

机构地区：[1]中国科学院长春应用化学研究所中国科学院生态环境高分子材料重点实验室,长春130022 [2]中国科学技术大学应用化学与工程学院,合肥230026

出　　处：《高分子学报》2023年第3期356-364,共9页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号U21A2089,51873211)资助项目

摘　　要：从生物质原料3,4-二氢吡喃出发,合成了可再生环状缩醛酯单体(H-AE),从结构上看,该单体在γ-丁内酯中引入了缩醛单元,在开环聚合过程中,通过释放甲醛分子有希望在温和条件下得到聚(γ-丁内酯).选用合适的Lewis酸碱对催化剂,基本抑制了聚合过程中的链回咬副反应,实现了单体的可控聚合.详细研究了催化剂的酸/碱性强度及其位阻大小对于合成的聚合物的组成和比例的影响,通过设计和优化催化剂的结构,实现了聚合物中聚丁内酯单元和聚缩醛酯单元比例的调控.对所得聚合物进行了1H-NMR、13C-NMR及扩散排序核磁共振(DOSY)表征,结合聚合过程的核磁与SEC监测,证实所得聚合物为丁内酯与缩醛酯的无规共聚物.根据实验数据和表征结果,推测聚合遵循Lewis酸碱对调控的阴离子开环聚合机理,酸碱催化剂共同稳定活性链末端,实现了亲核进攻和甲醛的脱除.A seven-membered cyclic acetal ester monomer(H-AE)was synthesized from biomass-based 3,4-dihydropyran.Structurally,this monomer introduces an acetal unit intoγ-butyrolactone,which promises to afford poly(γ-butyrolactone)under mild conditions by releasing formaldehyde molecules during ring-opening polymerization.The judicious choice of Lewis pair catalysts substantially inhibits the back-biting side reactions during the polymerization process and realizes the entropy driven polymerization.We carefully studied the effects of the acid/basicity and the steric hindrance of the catalyst on the composition of the synthesized polymers.By designing and optimizing the catalyst structure,regulation of the ratio of poly(γ-butyrolactone)and poly(acetal esters)units was realized.With the help of NMR and SEC characterization of the polymer and the polymerization process,we confirmed that the obtained polymer is a random copolymer of poly(γ-butyrolactone)and poly(acetal ester).Finally,based on the experimental data and characterization results,we speculate that the polymerization follows the Lewis-pair mediated anionic ring-opening polymerization mechanism.Lewis acid and Lewis base act together on the active anion chain end to afford appropriate affinity and supress the back-bite side reaction while ensuring the release of formaldehyde.

关 键 词：开环聚合 Lewis酸碱对 环状缩醛酯 聚(γ-丁内酯) 

分 类 号：TQ316.341[化学工程—高聚物工业] TQ426