Exploiting Addition-Fragmentation Reactions to Produce Low Dispersity Poly(isobornyl acrylate) and Blocky Copolymers by Semibatch Radical Polymerization

Abstract

Solution radical homopolymerization of isobornyl acrylate (iBoA) under starved-feed higher temperature conditions unexpectedly leads to polymer product with low dispersity (<1.3) compared to the polymerization of butyl acrylate (BA) under identical conditions. Both backbiting and β-scission reactions occur, as the poly(iBoA) product contains close to 100% terminal double bond (TDB) functionality. However, the addition of monomer to the midchain radicals formed by backbiting is sterically hindered, greatly reducing both short and long-chain branching. The poly(iBoA) macromonomer functions as an excellent addition-fragmentation agent, not only lowering dispersity but also providing a means to efficiently produce blocky acrylate copolymers through sequential monomer feeding in the starved-feed semibatch process.

Keywords: addition-fragmentation; branching; isobornyl acrylate; macromonomer; molar mass distribution; radical polymerization.