High transparent polyimides containing pyridine and biphenyl units: Synthesis, thermal, mechanical, crystal and optical properties

摘要

Two series of isomeric pyridine-containing aromatic diamine monomers, 2,2 '-bis(5-amino-2-pyridinoxy) biphenyl (2a), 4,4 '-bis(5-amino-2-pyridinoxy)biphenyl (2b), and 4,4 '-bis(5-amino-6-methyl-2pyridinoxy)biphenyl (2c), 4,4 '-bis(5-amino-3-methyl-2-pyridinoxy)biphenyl (2d), 4,4 '-bis(5-amino-4methyl-2-pyridinoxy)biphenyl (2e) were successfully synthesized. Aimed at clarifying the structure-property relationships of containing pyridine and biphenyl high-performance polymers, polyimides PI(1-5) were synthesized via a two-step thermal imidization derived from 2b and various commercially aromatic anhydrides and polyimide PI-(6-9) was synthesized derived from 2,2 '-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2a, 2c, 2d and 2e. Furthermore, comparative studies on their properties including solubility, thermal and mechanical, optical properties, and crystalline were thoroughly performed. Some property differences of the isomers caused by the sequence changes were found. (C) 2015 Elsevier Ltd. All rights reserved.