AMPHIPHILIC COMB-SHAPED POLYMERS FROM POLY(ETHYLENE GLYCOL) MACROMONOMERS

Comb-shaped amphiphilic graft copolymers composed of hydrophobic backbones and hydrophilic side chains were prepared by radical copolymerization of poly (ethylene glycol) monomethacrylate macromonomers, and methacrylate and acrylate comonomers in toluene. The copolymerizations were very sensitive to the reaction conditions, and insoluble cross-linked gels were easily formed. The yields of soluble copolymers were affected by the initiator concentration, the macromonomer concentration, and the choice of chain transfer agents and comonomers. Solubilities of the copolymers in water or methanol were found to depend on the sizes and the numbers of the PEG side chains. The copolymers showed surface activity with CMC:s in the order of 0.1-1.5 g/L and surface tensions of 36-56 dyn/cm. When tested as emulsifiers most of the copolymers gave oil-in-water type emulsions at room temperature. Polymers carrying MPEG 2000 side chains were crystalline with melting points of 38-44-degrees-C, while those based on PEG 400 and 1000 were mostly amorphous with glass transition temperatures between -55 and -60-degrees-C.