Atom transfer radical polymerization of styrene initiated by α,α dibromotoluene and catalyzed by copper (I) bromide/2,2′ bipyridine was carried out.The produced polymers had narrow molecular weight distributions an...Atom transfer radical polymerization of styrene initiated by α,α dibromotoluene and catalyzed by copper (I) bromide/2,2′ bipyridine was carried out.The produced polymers had narrow molecular weight distributions and controlled molecular weights that were proportional to monomer conversion.In order to show that α,α dibromotoluene is a bifunctional initiator for atom transfer radical polymerization of styrene,polymerization of styrene using a mixture of 1 phenyl ethyl bromide and α,α dibromotoluene initiators was also carried out.The GPC trace of obtained polystyrene exhibited bimodal distribution.The peak appearing at lower elution time corresponds to polymer from α,α dibromotoluene and the other one corresponds to polymer from 1 phenyl ethyl bromide.The ratio of peak molecular weight of the polymer from α,α dibromotoluene to that from 1 phenyl ethyl bromide was found to be close to two,confirming that the polymer from α,α dibromotoluene grows from both ends of the polymer chain.Furthermore,the ratio of the two peak surface area changed with the molar ratio of α,α dibromotoluene to 1 phenyl ethyl bromide.展开更多
The atom transfer radical polymerization of styrene was carried out with an α-haloketone, 2-bromocyclohexanone, as the initiator in the presence of CuBr/Cu/2,2′-bipyridine or CuBr/ N,N,N′,N″,N″-pentamethyldiethyl...The atom transfer radical polymerization of styrene was carried out with an α-haloketone, 2-bromocyclohexanone, as the initiator in the presence of CuBr/Cu/2,2′-bipyridine or CuBr/ N,N,N′,N″,N″-pentamethyldiethylenetriamine catalytic system. The polymerization proceeded in a living fashion with that the number average molecular weight increased linearly with the increase of monomer conversion and the polydispersity was relatively low through the polymerization process, especially with CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine as the catalyst. The initiation efficiency of 2-bromocyclohexanone in both catalysis systems was about 80%. 1H NMR and 13C NMR verified the presence of 2-oxocyclohexyl and bromine atom at the both ends of polystyrene chains respectively, which were derived from the 2-bromocyclohexanone.展开更多
原子转移自由基聚合反应(atom transfer radical polymerization,ATRP)是纤维素及其衍生物进行修饰改性的一种有效途径。通过ATRP对纤维素及其衍生物进行改性,可以得到不包含相应均聚物的纯接枝产物,且接枝链的长度及分子量分布均可控...原子转移自由基聚合反应(atom transfer radical polymerization,ATRP)是纤维素及其衍生物进行修饰改性的一种有效途径。通过ATRP对纤维素及其衍生物进行改性,可以得到不包含相应均聚物的纯接枝产物,且接枝链的长度及分子量分布均可控。通过ATRP不仅可对纤维素进行本体改性,还可对其进行表面改性。原子转移自由基聚合方法在纤维素及其衍生物改性方面的应用Ⅰ″一文介绍了通过ATRP对纤维素及其衍生物进行本体改性的研究进展。本文概述了通过ATRP对纤维素及其衍生物进行表面改性的研究进展。展开更多
文摘Atom transfer radical polymerization of styrene initiated by α,α dibromotoluene and catalyzed by copper (I) bromide/2,2′ bipyridine was carried out.The produced polymers had narrow molecular weight distributions and controlled molecular weights that were proportional to monomer conversion.In order to show that α,α dibromotoluene is a bifunctional initiator for atom transfer radical polymerization of styrene,polymerization of styrene using a mixture of 1 phenyl ethyl bromide and α,α dibromotoluene initiators was also carried out.The GPC trace of obtained polystyrene exhibited bimodal distribution.The peak appearing at lower elution time corresponds to polymer from α,α dibromotoluene and the other one corresponds to polymer from 1 phenyl ethyl bromide.The ratio of peak molecular weight of the polymer from α,α dibromotoluene to that from 1 phenyl ethyl bromide was found to be close to two,confirming that the polymer from α,α dibromotoluene grows from both ends of the polymer chain.Furthermore,the ratio of the two peak surface area changed with the molar ratio of α,α dibromotoluene to 1 phenyl ethyl bromide.
文摘The atom transfer radical polymerization of styrene was carried out with an α-haloketone, 2-bromocyclohexanone, as the initiator in the presence of CuBr/Cu/2,2′-bipyridine or CuBr/ N,N,N′,N″,N″-pentamethyldiethylenetriamine catalytic system. The polymerization proceeded in a living fashion with that the number average molecular weight increased linearly with the increase of monomer conversion and the polydispersity was relatively low through the polymerization process, especially with CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine as the catalyst. The initiation efficiency of 2-bromocyclohexanone in both catalysis systems was about 80%. 1H NMR and 13C NMR verified the presence of 2-oxocyclohexyl and bromine atom at the both ends of polystyrene chains respectively, which were derived from the 2-bromocyclohexanone.
文摘原子转移自由基聚合反应(atom transfer radical polymerization,ATRP)是纤维素及其衍生物进行修饰改性的一种有效途径。通过ATRP对纤维素及其衍生物进行改性,可以得到不包含相应均聚物的纯接枝产物,且接枝链的长度及分子量分布均可控。通过ATRP不仅可对纤维素进行本体改性,还可对其进行表面改性。原子转移自由基聚合方法在纤维素及其衍生物改性方面的应用Ⅰ″一文介绍了通过ATRP对纤维素及其衍生物进行本体改性的研究进展。本文概述了通过ATRP对纤维素及其衍生物进行表面改性的研究进展。
