Study of Aromatic Polyimides Containing Cyano Groups

Aromatic polyimides containing cyano groups have been synthesized by solution polycondensation reaction of an aromatic diamine having cyano and ether groups, with various aromatic dianhydrides containing flexible groups such as carbonyl and hexafluoroisopropylidene. The properties of these polyimides were compared with those of related polymers based on rigid aromatic dianhydrides, such as biphenyltetracarboxylic and pyromellitic dianhydride, and the same cyano containing diamine. The polymers were easily soluble in polar organic solvents, such as N-methylpyrrolidinone, N,N-dimethylacetamide and N,N-dimethylformamide and exhibited remarkable film forming ability, except for polyimide derived from pyromellitic dianhydride. They showed high thermal stability, with initial decomposition temperature being above 400 °C and glass transition temperature in the range of 210—260 °C. Conformational rigidity parameters of these polymers have been calculated by Monte Carlo method with allowance for hindered rotation....