In order to clarify whether Atom Transfer Radical Polymerization（ATRP） method could be extended to free radical ring-opening polymerization, the polymerization of a kind of unsaturated cyclic acetal: 5,6-benzo-2-methylene-1,3-dioxepane（BMDO） in the presence of α,α-dibromoxylene as the initiator and CuBr/2,2-bipyridine as the catalyst and ligand at 120 ℃ was investigated. IR, 1H NMR and 13C NMR spectra of the polymer obtained showed that BMDO underwent quantitatively ring-opening polymerization and linear polyesters were prepared. GPC curves indicated that the polyesters had a narrower molecular weight distribution. Molecular weight of the polyesters could be controlled by polymerization time and adjusting the molar ratio of monomer/intiator consumed. The polymers with narrower polydispersities were obtained, and first-order kinetics of polymerization was observed. These facts proved that BMDO underwent “living” free radical ring-opening polymerization. And this is the firsr report on the “living” free radical ring-opening polymerization of unsarurated cyclic acetal using atom transfer radical polymerization method. The results of ln（[M]0）/[M]) against polymerization time, Mn vs. conversion, and molecular weight distribution of the polymers are indicative of the “living” polymerization process.
Hyperbranched polyacrylate copolymers were synthesized by self\|condensing vinyl copolymerization (SCVCP) of 2\|[(2\|bromopropionyl)oxy]ethyl acrylate(BPEA) and methyl acrylate(MA) in the presence of a tetrafunctional initiator(THABI).The structures of the polymers obtained were characterized by 1H\|NMR and SEC/refractive index(RI)/right anagle laser light scattering(RALLS)/differential viscometer(DV).Molecular weight(MW),molecular weight distribution(MWD) and degree of branching(DB) were influenced by conversion and initial feed molar ratio of BPEA,MA and THABI.The addition of THABI can narrow the MWDs of the polymers obtained.The results are consistent with our simulation result.
