高刺激灵敏度的触发式自降解超支化聚邻苯二甲醛材料的构筑

Aiming at development of fast response and highly sensitive self-immolative polyphthalaldhyde (PPHA) towards weak stimulus, this project develops a series of PPHAs with hyperbranched topology that bears strikingly increased detective end-groups when comparing with linear PPHAs. By using two different strategies, including self-condensing vinyl polymerization (SCVP) and multi-functional monomer copolymerizations, hyperbranched PPHAs with controllable molecular structures can be successfully achieved. Systematic investigations, including the inimer structures and ratios, the catalyst types, the loading multifunctional phthalaldehydes, etc., were implemented, producing a series of hyperbranched PPHAs with tunable chemical compositions, molecular weights and branching degrees. The relationship between the response kinetics to stimulus and structure parameters of hyperbranched PPHA is built via measuring the responses of PPHA film in various stimulus at different concentrations. Quantitative relationships between the detection terminus and response rates is further established by using star PPHAs with precisely designed arms as model. This project may open a new avenue to fabricate self-immolative polymers with high selectivity and sensitivity.

本项目针对触发式自降解聚合物聚邻苯二甲醛在实际应用中对刺激源信号灵敏度低的问题，从改变拓扑结构进而增加链末端响应基团的浓度出发，采用自缩合乙烯基聚合法和多官能度单体共聚法两种策略，构筑高刺激灵敏度的超支化聚邻苯二甲醛材料。通过系统研究聚合条件，如有机碱催化剂种类及用量、单体-引发剂（inimer）及多官能度单体配比、单体浓度等，得到结构参数可控的系列超支化聚合物，并在不同环境下考察其对刺激源的响应动力学，阐明聚合物结构参数对刺激响应灵敏度的作用机制。本项目进一步以臂数（末端基团数）明确、臂长精确可控的星形聚合物为模型，将末端基团数与刺激响应速率相关联，揭示末端基团数与灵敏度之间的定量关系，为拓宽聚邻苯二甲醛材料的使用范围奠定理论基础，为深刻认识触发式自降解聚合物灵敏度的调控机制，丰富高灵敏度触发式自降解聚合物的结构设计提供思路。

刺激响应聚合物是当前高分子化学新近发展的重要研究领域之一。线形聚邻苯二甲醛是一类典型的触发式自降解聚合物，然而其响应灵敏度较低，实际应用时需要输入较多的刺激源。针对这一问题，本项目基于线形聚邻苯二甲醛的末端响应特点，从改变拓扑结构进而增加链末端基团数量的思路出发，构筑了具有高刺激响应灵敏度特点的超支化聚邻苯二甲醛。设计并合成了单体-引发剂（inimer），通过inimer与邻苯二甲醛单体共聚合，成功实现了分子结构参数及支化度可控的超支化聚邻苯二甲醛的制备。研究并建立了聚合物支化度对其刺激响应行为的影响机制，数据表明，Inimer的投入量为5 mol%时，其刺激响应灵敏度最高。研究了线形及支化聚邻苯二甲醛的热力学性能，超支化聚邻苯二甲醛比线形聚合物的热降解温度提高了近115oC，即极大地提升了线形聚合物热稳定性。通过项目开展的研究工作及取得的成果，成功实现了具有高刺激响应灵敏度的超支化聚邻苯二甲醛的制备，为高灵敏度刺激响应聚合物的开发提供了思路。在本项目支持下申请人发表SCI论文3篇，申请发明专利2项，授权发明专利1项。