Amphiphilic Biodegradable Poly(ε-caprolactone)-Poly(ethylene glycol) - Poly(ε-caprolactone) Triblock Copolymer Synthesis by Maghnite-H+ as a Green Catalyst

Amphiphilic biodegradable (PCL-PEG-PCL) triblock copolymers have been successfully prepared by the ring opening polymerization of epsilon-caprolactone (CL) in the presence of poly(ethylene glycol) (PEG) at 80 degrees C employing Maghnite-H+ a non-toxic Montmorillonite clay as catalyst. Maghnite-H+ reacts as a solid source of protons to induce epsilon-caprolactone polymerization. The triblock architecture, molecular weight and thermal properties of the copolymers were characterized by NMR spectra, GPC and DSC analyses. The effect of Maghnite-H+ proportion and PEGs on the rate of copolymerization and on average molecular weight of resulting copolymers was studied. A cationic mechanism for the copolymerization reaction was proposed.