SYNTHESIS AND PROPERTIES OF NEW ALTERNATING COPOLYETHERS CONTAINING PENDENT CYANO GROUPS

A general method for the preparation of polyarylether alternating copo lymers containing pendent cyano groups has been developed. We found th at the activated aryl fluorides in 2-chloro-6-fluorobenzonitrile are s electively displaced by phenoxides to yield 3-chloro-2-cyanophenyl eth ers as the exclusive products. Utilizing this selectivity, several new , high molecular-weight, soluble polyarylether alternating copolymers containing pendent cyano groups were prepared by sequential reaction o f 2-chloro-6-fluorobenzonitrile with the potassium salts of two differ ent diphenols. Reaction of two moles of 2-chloro-6-fluorobenzonitrile with one mole of a diphenoxide yields a bis(3-chloro-2-cyanophenyl)eth er (bis-CCPE) as the only product. Subsequent reaction of a second bis phenoxide with the bis-CCPEs causes displacement of the activated chlo ro groups and formation of alternating copolymers. The copolymers were processable from solution to yield transparent, flexible films. At el evated temperatures the cyano groups undergo crosslinking reactions yi elding films with high solvent resistance. The glass transition temper atures of the resulting crosslinked films ranged from 156 to 254 degre es C depending on polymer structure and cure conditions.