Poly(amide acid) gels were first synthesized by the reaction of a poly(amid
e acid) with diisocyanates as crosslinking agents. Poly(amide acid) was syn
thesized from 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and
bis(4-amino-3-ethylphenyl)methane (DEDPM). From the change in the IR spectr
a, the key process of crosslinking was determined to be the decarboxylation
from the reaction product of the carboxyl group and isocyanate group. The
gels markedly change their volume with the composition change of NMP-water
mixed solvent. Thermal properties of the poly(amide acid) gels are also stu
died. (C) 2000 Elsevier Science B.V. All rights reserved.