Polyimide structure–property relationships. I. Polymers from fluorene‐derived diamines

Abstract

A series of fluorene and fluorenone diamines were polymerized with two aromatic dianhydrides, and the resulting polyamic acids were cyclodehydrated to aromatic polyimides. A study of the mechanical properties of the polyimide films disclosed they are among the stiffest reported to date, with an excellent retention of rigidity at elevated temperatures. Comparisons of the tensile properties and glass transition temperatures of the fluorene‐derived polymer films with those from the corresponding open‐chain polyimide films established that the unusual rigidity, especially at elevated temperatures, was in large part due to the contribution of the bulky, tricyclic fluorene (one) moieties in the polymer structures.