The Preparation And Structure-Properties Study Of Polyimide Fibers With Biphenyl Side Chains

Polyimides are a class of high performance polymers that, due to their combination of excellent thermal, chemical, electrical, and high-temperature mechanical properties, are widely used as high temperature insulators, coatings, adhesives and advanced composite matrices. One area that has received considerable attention in recent years is the side chain modification and functionalization of high performance polyimides. Introducing biphenyl side chains into polyimide chains as substitutes is very interesting because they can maintain mechanical properties and improve greatly processability at the same time, which can give a chance to adopt one-step process to prepare polyimide fibers. Based on research of polymerization, property of polymer solution, process of spinning and annealed method, systemic understanding of preparation process and controlling polymeric fiber structures can be obtained to discover polymer science and technology in procedure of polyimide fiber preparation, to establish solved methods and conception to further push forward development of polyimide fibers, and expand research or application field of side chain modification and functionalization of high performance polyimides. The studies in this dissertation have focused on the purpose to design chemical molecular structures and control polymer structures on multi-levels control in process. A series of diamines containing various side chains with biphenyl groups 2-(4-phenylphenoxy) ethyl 3,5-diaminobenzoate, 6-(4-phenylphenoxy)hexyl 3,5-diaminobenzoate, 6-(4-cyano-phenylphenoxy)hexyl 3,5-diaminobenzoate were synthesized using 3,5-dinitrobenzoic acid as starting material. Fourier...