Title: Colorless Semi-Alicyclic Copolyimides with High Thermal Stability and Solubility

Author: Zhongxu Lan, Chunyu Li, Yanlei Yu, Jia Wei *

Journal: Polymers, 2019, 11(8), 1319

Abstract:

A series of colorless copolyimide films with high thermal stability and goodsolubility are synthesized from (trifluoromethyl)biphenyl-4,4’-diamine (TFMB) with dierent 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA) to 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane (6FDA) dianhydride mole ratios through one-pot solution polycondensation. These copolyimide films exhibit excellent optical transparency (T400 > 90% and λ0 ~305-333 nm) with a thickness of 15 μm and good solubility in most organic solvents. The excellent optical properties are mainly attributed to the low inter- and intra-molecular charge transfer interactions due to the alicyclic structure and the strong electronegative CF3 groups. The glass transition temperature increases from 332 to 352 °C with increasing HPMDA content in the copolymers, while the thermal decomposition temperature is improved with increasing 6FDA content. These results indicate that the copolyimide films can be successfully utilized in the development of novel heat-resistant plastic substrates for the optoelectronic engineering applications.

Fulltext Link: https://pubmed.ncbi.nlm.nih.gov/31394813/

A series of CPI films with different mole ratio of HPMDA/6FDA were successfully obtained by copolymerizing of TFMB, 6FDA and HPMDA through one-pot solution polycondensation and the relationship between the polymer components and their properties was investigated. Incorporation of alicyclic dianhydride into fluorinated polyimide improves the optical transparency and Tg of the resulting polyimides. Meanwhile, the drawback of low decomposition temperature of alicyclic polyimide was compensated with increasing fluorinated dianhydride content. These colorless copolyimide films possess good solubility in most organic solvents, high thermal stability (Tg: 332–352 °C) and excellent optical properties (T400 > 90% and λ0 ~ 305-333 nm). Among the obtained polyimides, PI-40 shows best overall performance with high thermal stability and transmittance. This work provides new insights on preparing CPI films with a combination of good solubility, high thermal stability and excellent optical properties.