Reversible addition fragmentation chain transfer (RAFT) polymerization was used in the lcyclopolymerization of a symmetrical difunctional monomer, tert-butyl alpha-(hydroxymethyl)acrylate ether dimer. Cumyl dithiobenzoate (CDB) was chosen as the RAFT agent and N,N'-azobis(isobutyronitrile) (AIBN) was employed as the initiator. Polymerizations were carried out in xylene at 70 degrees C. Under tuned conditions, cyclic soluble polymers with six-membered tetrahydropyran repeat units were obtained. Polydispersities of the polymers were relatively low and molecular weights were close to the theoretical values. Factors affecting the RAFT mediated cyclopolymerization were investigated. The results indicate that initial monomer concentration, [CDBI]/[AIBN] ratios, and reaction temperatures change the rate and the control of the RAFT cyclopolymerization. The livingness of the cyclopolymers was shown through successful block copolymerization with n-butyl acrylate where the formers were used as the macro-chain transfer agents.