Modified aromatic polyimides with potential piezoelectric properties

Aromatic polyimides containing nitrile polar functional groups with potential piezoelectric properties have been synthesized by solution polycondensation of aromatic diamines having nitrile group with various aromatic dianhydrides. The polymers were easily soluble in polar aprotic solvents such as N-methylpirrolidone, N,N-dimethylformamide and N,N-dimethylacetamide. Thin transparent films having a thickness of tens of micrometers have been prepared from N-methylpyrrolidinone solutions by casting onto glass substrates. The polymers showed high thermal stability with decomposition temperature being above 430 degC and glass transition temperature in the range of 200-280 degC, with a large interval between glass transition and decomposition temperature