Linear cyclopolymers with 20- and 28- membered rings were synthesized respectively by ATRP.Cyclopolymerization was carried out using CuBr/PMDETA/EBiB as an initiating system with toluene as solvent

which favored intramolecular cyclization over that with DMSO as solvent.The polymerization kinetics showed that the rate of cyclopolymerization reduced with increasing the ring-size of the polymers.Cyclization efficiency of dialkylsilylene-tethered bismethacrylates is highly affected by the monomer concentration

with the increasing of the concentration of monomer

the cyclization efficiency decreases and PDI of polymer obtained becomes broad.The cyclic structures of the polymer were confirmed by the 1H-NMR spectroscopy and the cyclic degree of the polymers was determined by the end-group analysis of the cyclopolymers and GPC.1H-NMR spectroscopy indicated that the polymerizations proceeded with 95% cyclization for monomer A2 and 92% cyclization for monomer B2.The polymers show controlled molecular weights and narrow molecular weight distributions (Mw/Mn 1.3).The thermodynamic properties of the cyclopolymers was investigated by TGA.The results showed that the cyclopolymers have higher thermal stability (372 ℃) than poly(methyl methacrylate).