Initiators for continuous activator regeneration atom transfer radical polymerization （ICAR ATRP） of acrylonitrile was first conducted at various ambient temperatures （30-45 ℃）. The key to success is ascribed to ...Initiators for continuous activator regeneration atom transfer radical polymerization （ICAR ATRP） of acrylonitrile was first conducted at various ambient temperatures （30-45 ℃）. The key to success is ascribed to the usage of an appropriate low temperature radical initiator （2,2＇-azobis（2,4-dimethylvaleronitrile）） and a high reactivity catalytic system （CuBr2/Me6TREN）. The molar ratio of Cu catalyst tO AN as low as 1：20000 wa.s used to prepare well-defined polyacrylonitrile with controlled molecular weight and a narrow polydispersity index range of 1.08-1.30, while the monomer conversion was up to ca. 98%. The apparent activation energy of the polymerization was calculated to be 128.45 kJ/mol, suggesting that the polymerization strongly depended on reaction temperature. The very high chain-end functionality of the resultant polymer was confirmed by ^1H-NMR and GPC analyses as well as chain extension reaction.展开更多
A facile, safe and economical reducing agent, sodium hypophosphite（Na H2PO2·H2O）, has been successfully employed for ambient temperature living radical copolymerization of styrene（St） and methyl methacrylate...A facile, safe and economical reducing agent, sodium hypophosphite（Na H2PO2·H2O）, has been successfully employed for ambient temperature living radical copolymerization of styrene（St） and methyl methacrylate（MMA）. Such effective reducing agent significantly improved the reactivity of low reactive St monomers during the copolymerization, where the reactivity ratios of St and MMA were determined to be 0.50 and 0.36 by Finemann-Ross method. Thus the copolymerizations proceeded fast and showed typical living/controlled features, as evidenced by pseudo first-order kinetics of polymerization, linear increase in molecular weight versus monomer conversion, and low polydispersity index values. Effects of the concentration of reducing agent and the monomer feed ratio on the copolymerization were investigated in detail. Furthermore, gel permeation chromatography and 1H-NMR analyses as well as chain extension experiments confirmed the high chain-end functionality of the resultant copolymer.展开更多
基金the National Natural Science Foundation of China(Nos.21074127 and 20804044)the Key Project of Chinese Ministry of Education(No.212003)
文摘Initiators for continuous activator regeneration atom transfer radical polymerization （ICAR ATRP） of acrylonitrile was first conducted at various ambient temperatures （30-45 ℃）. The key to success is ascribed to the usage of an appropriate low temperature radical initiator （2,2＇-azobis（2,4-dimethylvaleronitrile）） and a high reactivity catalytic system （CuBr2/Me6TREN）. The molar ratio of Cu catalyst tO AN as low as 1：20000 wa.s used to prepare well-defined polyacrylonitrile with controlled molecular weight and a narrow polydispersity index range of 1.08-1.30, while the monomer conversion was up to ca. 98%. The apparent activation energy of the polymerization was calculated to be 128.45 kJ/mol, suggesting that the polymerization strongly depended on reaction temperature. The very high chain-end functionality of the resultant polymer was confirmed by ^1H-NMR and GPC analyses as well as chain extension reaction.
基金financially supported by the National Natural Science Foundation of China(No.21074127)
文摘A facile, safe and economical reducing agent, sodium hypophosphite（Na H2PO2·H2O）, has been successfully employed for ambient temperature living radical copolymerization of styrene（St） and methyl methacrylate（MMA）. Such effective reducing agent significantly improved the reactivity of low reactive St monomers during the copolymerization, where the reactivity ratios of St and MMA were determined to be 0.50 and 0.36 by Finemann-Ross method. Thus the copolymerizations proceeded fast and showed typical living/controlled features, as evidenced by pseudo first-order kinetics of polymerization, linear increase in molecular weight versus monomer conversion, and low polydispersity index values. Effects of the concentration of reducing agent and the monomer feed ratio on the copolymerization were investigated in detail. Furthermore, gel permeation chromatography and 1H-NMR analyses as well as chain extension experiments confirmed the high chain-end functionality of the resultant copolymer.
