Hasegawa, Masatoshi;Hirano, Daiki;Fujii, Mari;Haga, Misako;Takezawa, Eiichiro;Yamaguchi, Shinya;Ishikawa, Atsushi;Kagayama, Takashi published 《Solution-processable colorless polyimides derived from hydrogenated pyromellitic dianhydride with controlled steric structure》 in 2013. The article was appeared in 《Journal of Polymer Science, Part A: Polymer Chemistry》. They have made some progress in their research.Formula: C12H12N2O The article mentions the following:
This work presents novel colorless polyimides (PIs) derived from 1R,2S,4S,5R-cyclohexanetetracarboxylic dianhydride (H”-PMDA). Isomer effects were also discussed by comparing with PI systems derived from conventional hydrogenated pyromellitic dianhydride, i.e., 1S,2R,4S,5R-cyclohexanetetracarboxylic dianhydride (H-PMDA). H”-PMDA was much more reactive with various diamines than H-PMDA, and the former led to PI precursors with much higher mol. weights The results can be explained from the quite different steric structures of these isomers. The thermally imidized H”-PMDA-based films were colorless regardless of diamines because of inhibited charge-transfer interaction. In particular, the H”-PMDA/4,4′-oxydianiline system simultaneously achieved a very high Tg exceeding 300 °C, high toughness (elongation at break > 70%), and good solution processability. In contrast, the H-PMDA-based counterparts were essentially insoluble The outstanding solubility of the former probably results from disturbed chain stacking by its nonplanar steric structure. An advantage of chem. imidization process is also proposed. In some cases, a copolymerization approach with an aromatic tetracarboxylic dianhydride was effective to improve the thermal expansion property. The results suggest that the H”-PMDA-based PI systems can be promising candidates for novel high-temperature plastic substrate materials in electronic paper displays. A potential application as optical compensation film materials in liquid crystal displays (LCD) is also proposed in this work. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012. And 3-(4-Aminophenoxy)aniline (cas: 2657-87-6) was used in the research process.
3-(4-Aminophenoxy)aniline is one of ethers-buliding-blocks. Ethers lack the hydroxyl groups of alcohols. Without the strongly polarized O―H bond, ether molecules cannot engage in hydrogen bonding with each other. Formula: C12H12N2OEthers do have nonbonding electron pairs on their oxygen atoms, however, and they can form hydrogen bonds with other molecules (alcohols, amines, etc.) that have O―H or N―H bonds.
Reference:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem