芳香族聚酰亚胺合成新方法与新型高性能聚合物材料

Polyimides are strategic and fundamental raw materials indispensable to economic construction, progress in science and technology, social development, and national security. The preparation of aromatic polyimides is frequently accomplished by a two-stage process due to their insoluble and infusible property. The first stage involves an amidation reaction carried out in a polar aprotic solvent to produce a high-molecular-weight poly(amic acid). Processing of the polymer into the desired physical form of the final product can be accomplished only prior to the second stage, where the poly(amic acid) is cyclodehydrated to the polyimide by heating at high temperatures. This process endures several drawbacks. The poly(amic acid) is prone to hydrolytic cleavage and has relatively poor storage stability unless kept cold and dry during storage. The second-stage solid-state cyclization reaction may cause decomposition of polymer main chain. And the removal of low molecular mass by-products produces defects. All these provent the full achievement of potential advantages of polyimides. In this project, we plan to development a novel synthetic route to aromatic polyimides based on a new imidization reaction we found recently. By a combination of practical study and theoretical calculation, the reaction mechanism, kinetics and compounds suitable for this reaction will be investigated.The formation, transition, and mediation of chain structure and condensed state structure of precursor polymers during polycondensation and imidization will also be studied. Liquid crystalline precursor polymers will be designed and prepared to obtain polyimides with high strength and high modulus as well as proprietary intellectual property rights. The implementation of this project will lay the foundations of developing a unique theory for the structure design and controlled preparation of high performance polyimides.

聚酰亚胺是涉及经济建设、科技进步、社会发展和国家安全等众多领域的不可或缺的战略物质和重要基础材料。由于不熔不溶导致的成型加工困难，先合成可加工性好的前驱体聚合物，然后制备实用制品和高温环化是芳香族聚酰亚胺工程化最常用的工艺路线，但存在着前驱体溶液不稳定、高温环化时主链易降解、小分子副产物的脱除会产生结构缺陷等问题，制约了其潜在性能的充分发挥。该课题拟基于申请人最近发现的一个酰亚胺化新反应，建立芳香族聚酰亚胺合成的新途径和新单体体系，从根本上克服现有合成工艺的固有缺点。采用实验研究与理论计算相结合的方法深入、系统地研究新亚胺化反应的机理、动力学及适用范围，了解前驱体聚合物的合成和亚胺化过程中链结构和聚集态结构形成及演变的规律，掌握有效的调控手段。设计、合成液晶性前驱体聚合物，获得力学性能优异的聚酰亚胺材料，形成自主知识产权，为发展我国独特的高性能聚酰亚胺材料结构设计和可控制备理论奠定基础。

利用经典的克莱森重排反应，在芳香、半芳香聚酰胺主链芳环上同时引入极性羟基与不饱合烯丙基，研究了其作为上浆剂改善芳纶增强橡胶、环氧树脂复合材料界面结构的性能。基于申请人发现的一个酰亚胺化新反应，提出芳香聚酰亚胺合成的新途径和新单体体系，部分克服现有合成工艺的固有缺点。采用实验研究与理论计算相结合的方法，研究了该亚胺化反应的机理和动力学，了解了前驱体聚合物亚胺化过程中链结构和聚集态结构形成及演变的规律。设计、合成了溶解性较好的前驱体聚合物和芳香聚酰亚胺，根据新单体体系的结构特点和反应活性，进行低温溶液缩聚反应；系统研究了反应动力学和链结构的生长机制和调控手段，发展了适合新型芳香族聚酰胺分子量、分子量分布及链结构表征的方法，制备出性能稳定的新型前驱体聚合物。研究亚胺化反应机理和动力学，了解温度、气氛组成、催化剂、前驱体颗粒尺寸等条件的影响；探讨前驱体在溶液中的稳定性及亚胺化前后聚合度的变化，建立调控亚胺化反应过程和表征聚合物结构的方法。设计、合成了两类具有代表性的含有多个甲基的芳香族聚酰胺前驱体，将其制备成液晶溶液，并进行液晶纺丝，得到含甲基的芳香族聚酰胺纤维，经过热处理将其转化为聚酰亚胺纤维，得到有序度高的新型聚酰亚胺纤维，初步优化了单体和聚合物的结构。探索纺丝过程凝胶化、相转变机理和影响因素；研究了化学结构对聚合物链间相互作用、链堆积和聚集态结构的影响。分析了初生薄膜、初生丝受热亚胺化反应动力学，探讨温度、时间、外加张力等的影响。为发展我国独特的高性能聚酰亚胺材料结构设计和可控制备理论奠定基础。发表3篇SCI收录论文，获授权3件中国发明专利，新申请4件中国发明专利；作为会议主席主办Symposium on Asymmetric Polymerization and Chiral Functional Materials国际学术会议；在国际、国内学术会议各作邀请报告2次。