Functionalized multiarm poly(ε-caprolactone)s:: Synthesis, structure analysis, and network formation

The purpose of this research was to synthesize and characterize a novel class of four-arm, star-shape biodegradable polymers having double-bond functionality as a precursor for free-radical polymerization, with unsaturated monomers or macromers or photocrosslinking for network formation. The synthesis involved two basic steps. First, hydroxyl-functionalized four-arm poly(epsilon-caprolactone)s (PPCL-OH) were synthesized by the ring-opening polymerization of epsilon-caprolactone in the presence of pentaerythritol and stannous octoate. Second, double-bond-functionalized four-arm poly(epsilon-caprolactone)s (PPCL-Ma) were synthesized by reacting PPCL-OH with maleic anhydride in the melt at 130degreesC. Quantitative conversion of hydroxyl functionality in PPCL-OH to double-bond functionality was achieved for low molecular weight PPCL-OH. Both the PPCL-OH and the PPCL-Ma were characterized by FTIR, H-1-NMR, C-13-NMR, SEC, and DSC. The capability of the double-bond-functionalized four-arm poly(epsilon-caprolactone)s (PPCL-Ma) to form network structures was preliminarily shown by photocrosslinking PPCL-Ma. (C) 2002 Wiley Periodicals, Inc.