The confined crystallization behavior of polycaprolactone(PCL)in thin and ultrathin films was studied by AFM(atomic force microscopy)．It was found that the crystalline morphology of PCL depended on the film thickness．When the thickness d>2Rg(radius of gyration)

the polymer can crystallize into spherulites；when RgRg

the dense—branch morphology and dendrites could be found；when dRg

the“islands”structure could be obtained．Moreover．the effects of the crystallization temperature

substrate and the molecular weight on the cry-stalline morphology were discussed．It was shown that the crystallization of PCL in thin film is a diffusion-cuntrolled process

and it can be explained by diffusion—limited aggregation．