Structure–property studies on fluorinated polyimide isomers containing biphenyl moieties

Aimed at clarifying the structure–property relationships of fluorinated high-performance polymers, two series of polyimides were synthesized via a two-step thermal imidization derived from isomeric diamine monomers. Furthermore, comparative studies on their properties including solubility, thermal properties, contact angles, refractive indices, dielectric constants and gas permeability were thoroughly performed. Some property differences of the isomers caused by the sequence changes were found.