Synthesis and copolymerizations of 3,3‐difluorocyclobutene‐1‐carbonitrile

Abstract 3,3‐Difluorocyclobutene‐1‐carbonitrile (DFCB) was synthesized via cycloaddition of 1‐chloro‐2,2‐difluoroethylene and acrylonitrile, followed by dehydrochlorination with 1,4‐diazabicyclo[2.2.2]octane in tetrahydrofuran. Unlike cyclobutene‐1‐carbonitrile, this monomer did not homopolymerize either under radical or anionic conditions. As an electron‐poor monomer it copolymerized in the presence of free radicals with electronrich monomers such as styrene in good yield. It also copolymerized with electron‐poor monomers such as acrylonitrile, although in lower yields. The extent of incorporation of DFCB in the copolymers also depended on the electronic characteristics of the comonomers: high incorporation occurred with electron‐rich monomers, low incorporation with electron‐poor monomers. One extremely electron‐poor monomer, trimethyl ethylenetricarboxylate, did not copolymerize with DFCB.