Synthesis and Characterization of Star-Branched Poly(ε-caprolactone)

Abstract

Three-dimensional star-branched poly(e-caprolactone) was synthesized by combining ring-opening polymerization and "living" free-radical polymerization. The "arm-first" approach was used. In the first step the func- tionalized poly(e-caprolactone) was synthesized as the side chains. Then a difunctional monomer, divinylbenzene (DVB), was used as end-linking agent to synthesize star-branched polymers via "living" free radical polymerization. The star- branched poly(e-caprolactone) with divinylbenzene core was characterized by gel permeation chromatography (GPC), proton nuclear magnetic resonance ( 1 H NMR), and differential scanning calorimetry (DSC). merization / Divinylbenzene / The synthesis of polymers with star-like or branched architecture has attracted much attention in recent years due to their special properties that arise from three- dimensional compact shape of the macromolecules. These architectures were usually synthesized through two approaches, i.e., the "arm-first" and the "core-first" methods. The "arm-first" approach involves the syn- thesis of the precursor arms with functional terminus followed by end-linking using a multifunctional agent. The advantage of the "arm-first" technique is that it can control the molecular structure of the arms that are usu- ally synthesized by living anionic, cationic, and free radical polymerizations. For example, high molecu- lar weight star-shaped polystyrenes were synthesized by living/controlled radical polymerization of styrene and subsequent linking by DVB or 1,1 � -(methylenedi-