SYNTHESIS AND PROPERTIES OF NEW ALTERNATING POLY(ARYL ETHER) COPOLYMERS CONTAINING CYANO GROUPS

A general method for the preparation of poly(aryl ether) alternating c opolymers containing pendent cyano groups has been developed. We found that the activated aryl fluorides in 2-chloro-7-fluorobenzonitrile ar e selectively displaced by phenoxides to yield 3-chloro-2-cyanophenyl ethers as the exclusive products. Utilizing this selectivity, several new, high molecular weight, soluble poly(aryl ether amide) and poly(ar yl ether ketone) alternating copolymers containing pendent cyano group s were prepared. The T(g)s of the copolymers ranged from 160 to 262 de grees C. The dielectric constants of the copolymers were characterized as a function of percent relative humidity. All of the copolymers wer e processable from solution to yield transparent, flexible films. At e levated temperatures the cyano groups undergo crosslinking reactions y ielding films with high solvent resistance. (C) 1997 Elsevier Science Ltd.