Synthesis of Heterotelechelic Poly(ethylene glycol) Macromonomers. Preparation of Poly(ethylene glycol) Possessing a Methacryloyl Group at One End and a Formyl Group at the Other End

Poly(ethylene glycol) (PEG) having a polymerizable methacryloyl group at one end and an aldehyde group at the other end was quantitatively synthesized. Potassium 3,3-diethoxy-1-propanoxide initiated the anionic polymerization of ethylene oxide to form an acetal-ended PEG having potassium alkolate at the ω chain end. By adding methacrylic anhydride to the reaction mixture, the ω end was quantitatively converted to the methacryloxy group. When the PEG with an acetal group at one end and a methacryloyl group at the other end was treated with 90% acetic acid solution, the hydrolysis of the acetal end group proceeded to form a PEG macromonomer possessing an aldehyde end group. The end groups were characterized by 1H NMR and MALDI-TOF-MS spectroscopies. Copolymerization of the aldehyde-PEG macromonomer with methacrylate monomers quantitatively gave the PEG graft polymer with an aldehyde group at the free end of the graft chain.