Lactone end-capped poly(ethylene oxide) as a new building block for biomaterials

This paper reports on the synthesis of a novel poly(ethylene oxide) (PEO) macromonomer, which can be copolymerized with epsilon-caprolactone (epsilon-CL) by ring-opening polymerization (ROP). PEO chains end-capped by an epsilon-caprolactone unit (gammaPEO(.)CL) have been synthesized by living anionic ring-opening polymerization of ethylene oxide (EO) initiated by the potassium alkoxide of 1,4-dioxaspiro[4.5]decan-8-ol, followed by derivatization of the acetal into a ketone and the Baeyer-Villiger oxidation of the ketone into a lactone. The end-capping of PEO by epsilon-CL was assessed by FTIR, MALDI-TOF, and H-1 NMR spectroscopy. This type of macromonomer is a precursor of amphiphilic comblike copolymers consisting of a biodegradable hydrophobic backbone of poly-(epsilon-caprolactone) (PCL) and hydrophilic PEO grafts. Copolymerization of gammaPEO(.)CL with epsilon-CL was successfully initiated by aluminum alkoxide.