The syntheses of the homopolymers and diblock copolymers by adding dithioester as chain transfer agent．First a series of monomers：methyl methacrylate (MMA)

butyl methacrylate (BMA)

methyl acrylate (MA)

ethyl acrylate (EA)

butyl acrylate (BA)

and styrene (St) were polymerized in bulk by Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization．AlI of these homopolymers (PMMA、PBMA、PEA、PBA、 PMA、PSt) have the controBable polymerization characteristics

the polydisporsity index(PDI)is narrow(1.08～1.30)．At the same reaction conditions the rate of polymerization of the methacrylate is the fastest

styrene is slower

acrylate is the slowest．The higher the reaction temperature

the faster the polymerization rate．The effects 0f the molar ratio of chain transfer agent to initiator on polymerization and the effects of conversion and reaction time on the molar mass characteristics of the prepared block copolymers were discussed．The diblock copolymers have the characteristics of the controlled／living radical polymerization

that is to say that the real molecular-weight of these copolymers is similar to the theoretical molecular-weight

and the polydispersity index is less than 1.80．When the molar ratio of ABIN to CTA is ranged from 1:3 to 1:6

the copolymers with PSt as the first block also have characteristics of the controlled／living radical polymerization．The 1H-NMR spectra of the homopolymer (PMMA) and copolymer (PMMA-b-PEA) showed that the synthesized polymers have functional groups

dithioester

at the end of these polymers．