Synthesis and characterization of polyimides from unsymmetrical diamine with cyano groups

A new diamine monomer containing cyano group, 2-cyano-4,4 ' -diaminodipheny l ether, was synthesized and polymerized to polyimides with several aromati c dianhydrides via two kinds of imidization methods, namely, thermal or sol ution imidization methods. By the thermal imidization method, tough, flexib le, and creasable polyimide films were obtained except the polyimide from p yromellitic dianhydride. The polyimides have high T-g values and are stable up to 500 degreesC in air. The polyimide made from the diamine and I,4 ' - oxyphthalic anhydride via solution imidization method was partially soluble in polar aprotic solvents, but it becomes soluble when the cyano groups ar e hydrolyzed.