A novel method for the synthesis of macrocyclic graft copolymers was developed through combination of anionic ring-opening polymerization (AROP) and atom transfer radical polymerization (ATRP).A linear α,ω-dihydroxy...A novel method for the synthesis of macrocyclic graft copolymers was developed through combination of anionic ring-opening polymerization (AROP) and atom transfer radical polymerization (ATRP).A linear α,ω-dihydroxyl poly(ethylene oxide) with pendant acetal protected hydroxyl groups (l-poly(EO-co-EEGE)) was prepared first by the anionic copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE).Then l-poly(EO-co-EEGE) was cyclized.The crude cyclized product containing the linear byproduct was hydrolyzed and purified by being treated with α-CD.The pure cyclic copolymer [c-poly(EO-co-Gly)] was esterified by reaction with 2-bromoisobutyryl bromide,and then used as ATRP macroinitiators to initiate polymerization of 2-(dimethylamino) ethyl methacrylate (DMAEMA),and a series of pH-and temperature-sensitive macrocyclic graft copolymers composed of a hydrophilic PEO as the ring and PDMAEMA as side chains (c-PEO-g-PDMAEMA) were obtained.The behavior of pH-and temperature-sensitive macrocyclic copolymers was studied in aqueous solution by fluorescence and dynamic light scattering (DLS).The critical micellization pH values of macrocyclic graft copolymers and their corresponding linear graft copolymers (l-PEO-g-PDMAEMA) were measured.Under the same conditions,the cyclic graft copolymer with the shorter side chains gave the higher critical micellization pH value.The c-PEO-g-PDMAEMA showed the lower critical micellization pH value than the corresponding l-PEO-g-PDMAEMA.The average hydrodynamic diameters (Dh) of the micelles were measured by DLS with the variation of the aqueous solution pH value and temperature.展开更多
结构可控聚合物的合成对于高分子材料结构与性能研究及应用具有重要的理论和实际意义。乙烯基聚硅氧烷广泛用于硅橡胶、硅树脂材料的合成与改性。以环硅氧烷[八甲基环四硅氧烷(D 4)、四甲基四乙烯基环四硅氧烷(D Vi 4)]为单体,采用阴离...结构可控聚合物的合成对于高分子材料结构与性能研究及应用具有重要的理论和实际意义。乙烯基聚硅氧烷广泛用于硅橡胶、硅树脂材料的合成与改性。以环硅氧烷[八甲基环四硅氧烷(D 4)、四甲基四乙烯基环四硅氧烷(D Vi 4)]为单体,采用阴离子开环聚合的方式制备乙烯基聚硅氧烷(Vi-PMVS),利用1 H NMR、29 Si NMR、FTIR表征分析产物的结构;根据29 Si NMR谱图和凝胶渗透色谱(GPC)分析分子量(M n)及其分布。重点探索乙烯基聚硅氧烷分子量与分子量分布的影响因素。结果表明:通过控制单体和封端剂的比值、催化剂的种类与用量、聚合温度和聚合时间等,可以调控乙烯基聚硅氧烷的分子量及其分布。其中单体的添加顺序及其方式对分子量的影响最为显著;当两种单体的投料比为1∶1,分批逐滴加入D 4和D Vi 4单体,聚合物的分子量分布最低,聚合物的分子量也可以得到很好控制。展开更多
基金support from the National Natural Science Foundation of China (20874013)
文摘A novel method for the synthesis of macrocyclic graft copolymers was developed through combination of anionic ring-opening polymerization (AROP) and atom transfer radical polymerization (ATRP).A linear α,ω-dihydroxyl poly(ethylene oxide) with pendant acetal protected hydroxyl groups (l-poly(EO-co-EEGE)) was prepared first by the anionic copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE).Then l-poly(EO-co-EEGE) was cyclized.The crude cyclized product containing the linear byproduct was hydrolyzed and purified by being treated with α-CD.The pure cyclic copolymer [c-poly(EO-co-Gly)] was esterified by reaction with 2-bromoisobutyryl bromide,and then used as ATRP macroinitiators to initiate polymerization of 2-(dimethylamino) ethyl methacrylate (DMAEMA),and a series of pH-and temperature-sensitive macrocyclic graft copolymers composed of a hydrophilic PEO as the ring and PDMAEMA as side chains (c-PEO-g-PDMAEMA) were obtained.The behavior of pH-and temperature-sensitive macrocyclic copolymers was studied in aqueous solution by fluorescence and dynamic light scattering (DLS).The critical micellization pH values of macrocyclic graft copolymers and their corresponding linear graft copolymers (l-PEO-g-PDMAEMA) were measured.Under the same conditions,the cyclic graft copolymer with the shorter side chains gave the higher critical micellization pH value.The c-PEO-g-PDMAEMA showed the lower critical micellization pH value than the corresponding l-PEO-g-PDMAEMA.The average hydrodynamic diameters (Dh) of the micelles were measured by DLS with the variation of the aqueous solution pH value and temperature.
文摘结构可控聚合物的合成对于高分子材料结构与性能研究及应用具有重要的理论和实际意义。乙烯基聚硅氧烷广泛用于硅橡胶、硅树脂材料的合成与改性。以环硅氧烷[八甲基环四硅氧烷(D 4)、四甲基四乙烯基环四硅氧烷(D Vi 4)]为单体,采用阴离子开环聚合的方式制备乙烯基聚硅氧烷(Vi-PMVS),利用1 H NMR、29 Si NMR、FTIR表征分析产物的结构;根据29 Si NMR谱图和凝胶渗透色谱(GPC)分析分子量(M n)及其分布。重点探索乙烯基聚硅氧烷分子量与分子量分布的影响因素。结果表明:通过控制单体和封端剂的比值、催化剂的种类与用量、聚合温度和聚合时间等,可以调控乙烯基聚硅氧烷的分子量及其分布。其中单体的添加顺序及其方式对分子量的影响最为显著;当两种单体的投料比为1∶1,分批逐滴加入D 4和D Vi 4单体,聚合物的分子量分布最低,聚合物的分子量也可以得到很好控制。
