以动态共价杂化实现热固性聚酰亚胺的自修复和降解再生的研究

Conventional thermoset polymers have highly crosslinked structures connected through irreversible covalent bonds. Although they usually exhibit excellent mechanical properties, they can only be heated and molded once, and lack of malleability and rehealability represent their potential drawbacks. Given the reversibility of imine bond formation through imine exchange reaction, imine-linked polymers (polyimines) exhibit dynamic and malleable nature. They can be heated and molded multiple times, and display self-healing property upon treatment with heat and/or water. However, compared to conventional thermoset polymers, the variety of polyimines that have been developed so far is still very limited, and their mechanical property, thermostability and processibility need significant improvement. The goal of this project is to design and synthesize amino-terminated imide-based oligomers (as macromonomers), which will be integrated into polyimines by reacting with dialdehyde and triamine crosslinkers through imine condensation reaction, thus achieving a novel class of polymers with molecular-level hybridization. We will systematically investigate the dependence of the hybrid materials’ mechanical property, thermostability and processibility on the composition (degree of polymerization, monomer structure) and flexibility of the imide oligomer components, thus revealing their structure-property relationship. Particularly, we will study the malleability, recyclability, and self-healing property of the resulting hybrid polymers, with the ultimate goal of obtaining a novel class of high-performance poly(imide-imine) hybrid polymers with multi-cycle malleability, full recyclability and self-healing property.

以共价键交联的热固性高分子材料难以多次成型，损坏后难以自修复和降解再生。新兴的动态共价（Dynamic Covalent, DC）化学的发展，实现了分子内共价键可逆的形成和断开。本项目以DC化学为工具，针对缩合型热固性聚酰亚胺（PI），通过合成氨基封端PI低聚物作为二胺单体，与含有DC亚胺键的聚亚胺在分子尺度上杂化，实现在热固性PI内引入DC键。研究PI低聚物的亚胺缩聚反应动力学，明确杂化材料基于亚胺键动态可逆特性所形成的自修复及降解机制，分析杂化材料的结构决定其力学、热学性能的规律。为探索延长热固性高分子材料使用寿命的新方法开拓途径，为构筑可锻造、自修复及可降解再生的高性能热固性高分子材料提供新的设计思路，为提升DC杂化材料综合性能，拓展DC聚合物材料的应用领域奠定基础，为深入认识将DC键在分子水平上的动态性质转化成聚合物材料的宏观性能的途径和规律提供实验和理论基础。

本项目通过动态共价杂化技术共获得11种酰亚胺PI单体，并研究了其亚胺缩聚制备PI低聚物的反应动力学；研究了杂化方式对动态共价聚合物机械性能和稳定性能的影响；在分子水平上利用动态亚胺化学构建了8种杂化聚酰亚胺PIm-PI膜材；研究了酰亚胺单体对PIm-PI杂化材料机械性能和热学性能的影响；研究了PIm-PI杂化材料中亚胺键交换动力学规律及降解机制；制备了10种基于动态共价化学的聚亚胺/石墨烯气凝胶导电复合材料，研究了导电增强相含量对机械性能和电学性能的影响，获得了161 S/m的高电导率；制备了12种基于动态共价化学的聚酰亚胺/石墨烯气凝胶复合材料，研究了单体结构和导电增强相含量对膜材形貌及电学性能的影响；构建了三维整体石墨烯气凝胶-聚亚胺复合材料，研究了石墨烯气凝胶制备条件及相对含量对复合材料力学性能和电学性能的影响，并进一步研究了其压电性能。构建了具有荧光特性的聚亚胺材料，研究了荧光单元引入方式（聚亚胺侧链或骨架）对材料机械性能和发光性能的影响。部分结果已在国内外高水平SCI期刊Chinese Chemical Letters、ACS Applied Nano Materials等发表带标注论文7篇，其中中科院一区论文2篇，Nature Index期刊论文1篇；获授权发明专利3项，申请发明专利2项；参加国内外学术会议交流3次；项目主要参与人员入选云南省千人计划青年项目；培养毕业博士1名和毕业硕士4名。研究结果为探索延长热固性高分子材料使用寿命的新方法开拓途径，为构筑可锻造、自修复及可降解再生的高性能热固性高分子材料提供新的设计思路，为深入认识将动态共价键在分子水平上的动态性质转化成聚合物材料的宏观性能的途径和规律提供实验和理论基础。