N-Isopropylacrylamide (NIPAAm) was introduced onto the surface of polypropylene (PP) films to form a layer of poly(N-isopropylacrylamide) (PNIPAAm) by UV-induced surface photograft polymerization reaction．Improvement on UV intensity and reaction temperature favored the increase of the grafting yield

yet it went through a maximum as monomer concentration was increased．Two photograft techniques

the xanthen-9-one pre-dipping method and dormant radical method

were tried and higher grafting yields were achieved by the latter．The existence of PNIPAAm grafted polymer layer was confirmed by FTIR

ESCA and SEM measurements．The acrylamide band Ⅰand Ⅱ in FTIR spectra of the grafted polymer shifted as the temperature changed

which revealed the temperature sensitivity of the grafted films．Moreover

a special sphere-like surface morphology of the NIPAAm layers due to the temperature-responsive behaviors was observed by SEM．