Spontaneous Alternating Copolymerization via Zwitterion Intermediates

This article describes a new concept of copolymerization which occurs spontaneously without any added catalyst. A nucleophilic monomer (M N ) combines with an electrophilic one (M E ) to generate a zwitterion [+] M N —M   E − , which is responsible for the initiation and propagation of copolymerization. Twenty‐three novel copolymerizations have been explored on the basis of the new concept. M N monomers which have been investigated are five‐ and six‐membered cyclic imino ethers, dihydro‐2(3 H )‐furanimine, an azetidine, a cyclic phosphinic acid ester and a Schiff base; the M E monomers include β‐propiolactone, a cyclic dicarboxylic acid anhydride, a sultone, acrylic acid, acrylamide, a β‐hydroxyalkyl acrylate and ethylenesulfonamide. In most combinations, alternating 1 : 1 copolymers were produced. In addition to the above‐mentioned combinations, the alternating 1 : 1 copolymerization of cyclic phosphite with α‐keto acid was discovered.