Synthesis and characterization of star polymers made from simple, multifunctional initiators

A series of multifunctional molecules were synthesized, bearing either 4, 5, 6; or 10 sulfonyl chloride moieties, each capable of initiating atom transfer living radical polymerization. The general synthetic strategy was to prepare intermediates containing a plurality of phenyl groups and then chlorosulfonylate all of the available rings. These multifunctional initiators were used to synthesize star polymers via the core-first approach: Star polymers with relatively narrow molar mass distribution were successfully prepared, with a controlled number of arms and molar masses. The polymerization worked best with methacrylate esters and styrene, but acrylate esters polymerized very slowly under the reaction conditions employed. The number of arms in the polymers as a function of molar mass was determined by multidetector size-exclusion chromatography (SEC). Results of the arm number measurements by SEC were corroborated by experiments in which molar mass distributions were examined before and after the arms were cleaved chemically from the cores.