A series of water-soluble comb-like copolymers poly(acrylic acid)-g-poly[(ethylene glycol)methyl ether](PAA-g-mPEG)were synthesized by free-radical copolymerization of acrylic acid and mPEG monoacrylate macromonomers in iso-propanol solutions．The macromonomer was prepared by acrylation of monomethoxy poly(ethylene glycol)with aecrJoyl chloride．The characterization of the macromonomer and these copolymers was carried out by Fourier transform infra—red(FT—IR)and nuclear magnetic resonance(1H-NMR)spectroscopy．The glass transition temperature and melting temperature of the mPEG side—chains were detected by using DSC．It was found that the shorter the side chains

the higher the Tg is

and the mPEG side—chains in the copolymer could crystallize from the solution

but not easily from the melt．It implies that the movement of the side chains is strongly confined by the backbone and depends on the side chains length．Furthermore

the crystalline and phase morphologies of the comb—like copolymer films prepared by means of spin—coating on glass substrates were observed by phase contrast microscope and AFM. A lot of interesting crystalline and phase morphologies were found in the PAA—g—mPEG films．