Synthesis and properties of poly(amic acid)s and polyimides based on 2,2′,6,6′-biphenyltetracarboxylic dianhydride

Poly(amic acid)s (PAAs) having the high solution stability and transmittance at 365 nm for photosensitive polyimides have been developed. PAAs with a twisted conformation in the main chains were prepared from 2,2',6,6'-biphenyltetracarboxylic dianhydride (2,2',6,6'-BPDA) and aromatic diamines. Imidization of PAAs was achieved by chemical treatment using trifluoroacetic anhydride. Among them, the PAA derived from 2,2',6,6'-BPDA and 4,4'-(1,3-phenylenedioxy)dianiline was converted to the polyimide by thermal treatment. The heating at 300 degrees C under nitrogen did not complete thermal imidization of PAAs having glass-transition temperatures (T-g)s higher than 300 degrees C to the corresponding PIs. (c) 2006 Wiley Periodicals, Inc.