Synthesis and properties of poly(aryl ether sulfone)s with pendant trifluoromethyl group via nitro displacement reaction

Abstract

Two dinitro monomers with sulfone and trifluoromethyl groups which activate nitro leaving group were synthesized. One is 2,2'-bis(trifluoromethyl)-4,4'-dinitrophenyl-sulfone and the other is 3,3'-bis(trifluoromethyl)-4,4'-dinitrophenylsuIfone. These two monomers were prepared from 5-chloro-2-nitrobenzotrifluoride or 2-chloro-5-nitrobenzotrifluoride with sodium sulfide followed by oxidation of the resulting sulfide group with sodium perborate or chromium oxide. Polymerization of dinitro monomers with dihydroxy or dithiol comonomers produced poly(aryl ether sulfone)s and poly(aryl. thioether sulfone)s with low molecular weight. From the model reaction, it was found that the nitro displacement reaction was competing with the sulfone cleavage reaction because sulfone group was doubly activated and susceptible to SNAr reaction. This sulfone cleavage reaction is the primary reason of the low molecular weight of resulting polymers.