Synthesis of poly(ɛ-caprolactone-co-ethylene glycol) star-type amphiphilic copolymers by click chemistry and ring-opening polymerization methods

In this study, the synthesis of poly(ԑ-caprolactone-co-ethylene glycol) AAB star-type amphiphilic copolymers were carried out by use of a "click" chemistry reaction to block propargyl polyethylene glycol (propargyl-PEG) to terminally azide poly(ԑ-caprolactone) (PCL-N3). For this purpose, propargyl-PEG was synthesized by the reaction of PEGs (3000 Da, 2000 Da, 1500 Da, and 1000 Da) and propargyl chloride. Terminally chloride poly(ԑ-caprolactone) (PCL-Cl) was carried out by means of ring-opening polymerization (ROP) of ԑ-caprolactone (CL) and 3-chloro-1,2-propanediol. Synthesis of PCL-N3 was obtained by the chemical interaction of PCL-Cl and sodium azide. By reacting propargyl-PEG and PCL-N3, the star-type amphiphilic copolymers were obtained. The characterization of products was accomplished by using multiple instruments including 1H-nuclear magnetic resonance, Fourier-transform infrared spectroscopy, gel-permeation chromatography, thermogravimetric analysis, and elemental analysis techniques. The hydrophilic character of the copolymers was also explored by contact angels of the water drops on the polymer films.