Hydroxyl-functionalized three-arm poly(is an element of-caprolactone)s (PGCL-OHs) were synthesized by the ring-opening polymerization Of E-caprolactone in the presence of glycerol (as the core) and stannous octoate. The effect of the feed ratio Of E-caprolactone to glycerol on the ring-opening polymerization was studied. These three-arm PGCL-OHs were then converted into double-bond-functionalized three-arm poly(is an element of-caprolactone)s (PGCL-Mas) by the reaction of PGCL-OH with maleic anhydride in the melt at 130 degreesC. The quantitative conversion of hydroxyl functionality was achieved at a low molecular weight. The resulting PGCL-OH and PGCL-Ma were characterized with gel permeation chromatography, Fourier transform infrared, H-1 NMR, C-13 NMR, and differential scanning calorimetry.