Synthesis and Properties of Highly Fluorinated Polyimides

A series of polyimides was synthesized to facilitate the study of several structure/property relationships, including relative permittivity, moisture absorption, free volume, and viscoelastic transitions. This series was based on hexafluoroisopropylidene bis(phthalic anhydride) and various diamines, with the intention of having a number of fluorine/hydrogen and symmetric/asymmetric analog sets. Since several of the fluorinated diamines were exceptionally unreactive, a multistep polycondensation polymerization technique was developed to obtain materials of sufficient molecular weight for property evaluation. Effects of fluorine incorporation on the aforementioned properties are reported. © 1994, American Chemical Society. All rights reserved.