Transparent and soluble polyimide films containing 4,4′-isopropylidenedicyclohexanol (Cis-HBPA) units: Preparation, characterization, thermal, mechanical, and dielectric properties

To develop colorless and soluble polyimide films, cis -hydrogenated bisphenol A ( cis -HBPA) was successfully separated from HBPA isomers, and two novel monomers containing cis -HBPA unit, 4,4 ′ -(4,4 ′ -isopropenylbicyclohexyloxy) diphthalic anhydride (HBPADA) and 4,4 ′ -(4,4 ′ -isopropenylbicyclohexyloxy) dianiline (f) were designed and synthesized. PI–(1 – 5) were achieved from HBPADA and five kinds of aromatic diamines and PI – 6 from HBPADA and semiaromatic diamine f via a two-step thermal imidization. All the polyimides could afford flexible, tough, and transparent films with transparency as high as 86% at 450 nm. Surprisingly, the polyimides containing cis -HBPA unit exhibited excellent solubility not only in polar solvents such as N, N -dimethylacetamide, but also in low boiling solvents such as chloroform and dichloromethane. Additionally, analogues aromatic PI – 7 derived from 4,4 ′ -(hexafluoroisopropylidene)-diphthalic anhydride (6FDA) and 2,2-bis(4-aminophenyl)hexafluoropropane (e) was obtained for comparison with PI–(1 – 6) on aspects of thermal, mechanical, soluble, optical, electrical, and morphological properties. The structure-property relationships of PI–(1 – 7) were investigated in detail. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56 , 2115–2128