Synthesis of Biodegradable Amphiphilic Y-shaped Block Co-polymers via Ring-Opening Polymerization for Drug Delivery

Abstract

A series of novel Y-shaped biodegradable block co-polymers of poly(ε-caprolactone) (PCL) and poly(ethyl ethylene phosphate) (PEEP) (PCL–(PEEP)2) were synthesized via ring-opening polymerization (ROP) of EEP with bis-hydroxy-functional ROP initiator (init–PCL–(OH)2). The init–PCL–(OH)2 was synthesized by ROP of CL using 4-hydroxybutyl acrylate (HBA) as initiator and L-tartaric acid as catalyst in bulk, and subsequently the resulting vinyl-terminated PCL was end-capped by acetyl chloride, followed by Michael addition using excess diethanolamine. The Y-shaped co-polymers and their intermediates were characterized by 1H-, 13C-, 31P-NMR, FT-IR and gel-permeation chromatography. The results indicated that the molecular weight of the Y-shaped co-polymers increased with the increasing of the molar ratios of EEP to init–PCL–(OH)2 in the feed, while the PCL chain length was kept constant. The amphiphilic block co-polymers could self-assemble into micelles in aqueous solution, which was demonstrated by dynamic light scattering, 1H-NMR and atomic force microscopy. A study of controlled release of indomethacin indicated that the amphiphilic block co-polymers could potentially provide novel vehicles for drug delivery.