Diblock copolymer poly(methyl methacrylate)-b-poly(vinyl acetate) (PMMA-b-PVAc) was prepared by 1,1-diphenylethene (DPE) method. First, free-radical polymerization of methyl methacrylate was carried out with AIBN as initiator in the presence of DPE, giving a DPE containing PMMA precursor with controlled molecular weight. Second, vinyl acetate was polymerized in the presence of the PMMA precursor and AIBN, aid PMMA-b-PVAc diblock copolymer with controlled molecular weight was obtained. The formation of PMMA-b-PVAc was confirmed by H-1 NMR spectrum. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to detect the self-assembly behavior of the diblock polymer in methanol. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1581-1587, 2009