Cyclic amine initiation of polypivalolactone

Abstract

AbstractCertain monocyclic and polycyclic tertiary amines initiate polymerization of, and copolymerize with, pivalolactone. These comprise three‐, four‐, and five‐membered monocyclic amines and 1‐azapolycyclic amines. The polymerization proceeds in three steps: (a) initiation to form a cyclic amine/pivalate betaine, (b) propagation to yield a polylactone zwitterion by an anionic mechanism, and (c) interlinking by a carboxylate end attacking a cyclic amine end to incorporate amine as a comonomer in the chain. When polymerization is carried out at low temperatures, the more stable cyclic amine ring systems yield isolatable step b polymers. These polymeric zwitterions undergo step c by heating, even in the solid state. The mechanism suggests that, for the more labile cyclic amines, a lactone could be the initiator for polyamine formation by a cationic mechanism. Interlinking would lead to incorporation of lactone initiator. In intermediate cases, block copolymers would result. With a proper balance of reactivities, 1:1 alternating copolymers would be possible.