Synthesis of multisegmented polymers by RAFT using linear polytrithiocarbonates

Abstract

Two types of polytrithiocarbonates were synthesized by step-growth polymerization. Method A was based on SN2 reaction between di(trithiocarbonate) anions and α,α’-dibromidoesters, and method B was based on Huisgen 1,3-dipolar cycloaddition between dialkyne-terminated trithiocarbonate and diazide. These multifunctional chain transfer agents (mCTA) were employed in reversible addition-fragmentation chain transfer poly­merization of 2-hydroxyethyl acrylate and styrene giving multisegmented homopolymers and multiblock copolymers multi-(polystyrene-b-poly(4-vinylbenzyl chloride)). mCTA prepared by the method A controls well polymerization of styrene, while mCTA prepared by the method B more suits for polymerization of 2-hydroxyethyl acrylate. Multisegmented polymers and multiblock copolymers were analyzed by size exclusion chromatography with triple detection, 1H nuclear magnetic resonance and differential scanning calorimetry. Dispersity of multisegmented poli(2-hydroxyethyl acrylate) was high, varying from 4 to 7, while dispersity of its hidrolyzed product (one block of poli(2-hydroxyethyl acrylate)) was narrow and equal to 1.2. It was demonstrated that multisegmented and multiblock polymers could be synthesized by the use of RAFT chain transfer agent with multiple trithio­carbonate moieties, and dispersity of the products was dependent on dispersity of the used mCTA.