Preparation and characterization of amphiphilic poly(ethylene glycol) graft copolymers

Amphiphilic graft copolymers of alkyl methacrylates, methoxy poly(ethylene glycol) (PEG) acrylate, and acrylic acid were synthesized by free radical p olymerization. PEG graft copolymers with respect to structure, composition, and average molecular weight were characterized by FT-IR,H-1 NMR, and GPC. The critical micelle concentration and molar mass of the polymeric micelle s were determined by fluorescence spectroscopy using pyrene as the fluoresc ence probe and static laser light scattering, respectively. The formation o f polymeric micelles was influenced by the balance of hydrophobicity and hy drophilicity and other factors such as molecular weight of the copolymer pr oducts. The molar mass of polymeric micelles increased with mole content of hydrophobic comonomers. Loading capacity and weight average partition coef ficient for the pyrene molecules into polymeric micelles were estimated via fluorescence quenching by Cu2+. Fluorescence quenching studies of pyrene i ndicated that a loose structure of micelles was formed from the graft copol ymer containing high content of hydrophilic monomethoxy poly(ethylene glyco l) (mPEG) and acrylic acid.