Figure 1.
Structure of PCL–PEG–PCL triblock copolymers prepared by ring-opening polymerization of Ɛ-caprolactone by poly(ethylene glycol) diol with stannous octoate catalyst. (a) FT-IR spectrum of entry X showing characteristic ester stretch at 1721 cm−1; (b) 1H NMR spectrum of entry X with peak assignments.