Poly(ethylene oxide) (PEO) chains were capped at one end by ε-caprolactone (ε-CL), which is polymerizable by ring opening polymerization (ROP). These macromonomers (γPEO.CL) have been prepared by controlled anionic ring-opening polymerization (ROP) of ethylene oxide (EO) initiated by the potassium alkoxide of 1,4-dioxaspiro[4.5]decan-8-ol leading to PEO with a monomodal molecular weight distribution and low polydispersity (~1.1). The acetal has been hydrolyzed into a ketone, followed by the Baeyer-Villiger oxidation of it into the seven-membered lactone.

After purification, macromonomers have been characterized by 1H-NMR, SEC, IR and MALDI-Tof. It must be noted that the ω-hydroxyl-end-group of PEO has been previously methylated in order to prevent ROP of ε-CL to be initiated by this function.

This type of macromonomer is well-suited for the synthesis of amphiphilic comb-like copolymers consisting of a biodegradable hydrophobic backbone of PCL and hydrophilic PEO grafts. First attempts of copolymerization of γPEO.CL with ε-CL have been successfully achieved using aluminum alkoxide as initiator- either in solution or attached on a solid surface. Characterization of the amphiphilic graft copolymers is under current investigation.

In addition, an α-bifunctional PEO has been easily prepared by hydrolysis of the lactone end-group into acid-alcohol. These COOH and OH groups are now available for the synthesis of mikto-armed ABC star-shaped copolymers.

ε-CL-terminated PEO is thus a promising building block of surfactants to be used in biomedical applications, for drug delivery and surface modification of biomaterials.

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