Synthesis and structural analysis of functionalized poly (ϵ‐caprolactone)‐based three‐arm star polymers

Hydroxyl‐functionalized three‐arm poly(ϵ‐caprolactone)s (PGCL‐OHs) were synthesized by the ring‐opening polymerization of ϵ‐caprolactone in the presence of glycerol (as the core) and stannous octoate. The effect of the feed ratio of ϵ‐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(ϵ‐caprolactone)s (PGCL‐Mas) by the reaction of PGCL‐OH with maleic anhydride in the melt at 130 °C. 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, 1 H NMR, 13 C NMR, and differential scanning calorimetry.