Amphiphilic diblock copolymers, poly(methyl methacrylate)-b-poly(acrylic acid) (PMMA-b-PAA) and polystyrene-b-poly(acrylic acid) (PS-b-PAA), were prepared by 1,1-diphenylethene (DPE) method under mild conditions. Firstly, free radical polymerization of tert-butyl acrylate (tBA) was carried out with AIBN as initiator in the presence of DPE, giving a DPE-containing precursor, PtBA, with controlled molecular weight. Secondly, methyl methacrylate and styrene were polymerized in the presence of PtBA precursor, and PS-b-PtBA and PMMA-b-PtBA diblock copolymers with controlled molecular weights were obtained respectively. Finally, amphiphilic diblock copolymers, PMMA-b-PAA and PS-b-PAA, were prepared by hydrolysis of PS-b-PtBA and PMMA-b-PtBA. The formation of PS-b-PAA and PMMA-b-PAA was confirmed by H-1 NMR. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to detect the self-assembly behavior of the amphiphilic diblock polymers in tetrahydrofuran (THF).