共查询到20条相似文献,搜索用时 201 毫秒
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原子转移自由基聚合(ATRP)是一种新型的可控/活性聚合技术,现已广泛应用于聚合物分子结构设计、无机材料表面修饰、蛋白质检测以及生物大分子的分离和杀菌防污等.在此类反应过程中涉及的三大要素:单体、引发体系(引发剂、催化剂、配位剂)及反应介质,其中核心要素为ATRP引发剂,其结构与性质是ATRP反应成败的决定因素之一.本文在综述了小分子引发剂的种类与性质及ATRP的反应机理的基础上,着重综述了近年来官能团反应法、偶联反应法及自由基聚合法制备ATRP大分子引发剂的最新进展.同时还综述了大分子引发剂通过ATRP反应在聚合物结构设计中的应用,以及对无机材料和生物材料的表面修饰的最新进展,最后对ATRP引发体系的未来发展与应用进行了展望. 相似文献
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纳米SiO2粒子极易团聚,在有机介质中难以均匀分散,从而大大地限制了其优异性能的发挥,有必要对其进行化学改性处理。原子转移自由基聚合(atom transfer radical polymerization,ATRP)是对纳米SiO2粒子进行接枝改性的一种有效途径,通过ATRP对纳米SiO2粒子进行表面改性,可以制备集无机纳米粒子和聚合物的优点于一身的SiO2-聚合物复合材料,且接枝链的长度及分子量分布可控,拓展了纳米SiO2的应用领域。本文主要综述了ATRP、RATRP(reverse ATRP)、AGET ATRP(activators generated by electron transferATRP)和ARGET ATRP(activators regenerated by electron transfer ATRP)方法对纳米SiO2接枝改性的研究现状。 相似文献
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通过ARGET ATRP(电子转移催化剂再生原子转移自由基聚合)法,以甲基丙烯酸甲酯(MMA)、丙烯酸[N-甲基全氟己烷磺酰胺基]乙酯(C_6SA)为单体,利用干式化学接枝法合成的SiO_2-NH-Br为引发剂,分步接枝得到了表面性能优异的有机/无机复合微-纳结构材料SiO_2-P(MMA-b-C_6SA).该材料经氢氟酸刻蚀后,采用凝胶渗透色谱(GPC)测定了接枝聚合物的分子量及其分布,结果表明在纳米SiO_2表面生长出了分子结构可控的嵌段聚合物.透射电镜观察SiO_2-P(MMA-b-C_6SA)复合物形貌呈现均匀分散的球形颗粒,表明所制备的有机/无机复合物在有机溶剂中具有良好的分散性.热重分析结果表明,该材料化学结构均一,并具有良好的热稳定性.本文采用具有工业应用前景的ARGET ATRP法,将环境友好的含氟单体(C_6SA)接枝在无机粒子表面,赋予其低表面能特性,使其水接触角达到143°,HD的静态接触角达到90°,表现出了优异的疏水疏油性能,并具有自清洁的性能. 相似文献
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研究了光敏性聚合物刷修饰二氧化硅纳米粒子的制备及其乳化行为, 提供了一种制备新颖“胶体体”微胶囊的方法. 首先, 在二氧化硅纳米粒子表面引入原子转移自由基聚合(ATRP)引发剂分子, 通过表面引发ATRP得到含有香豆素侧基聚合物刷光敏性的纳米二氧化硅粒子(SiO2-PMMA-PCMA); 然后, 以该粒子为乳化剂制备油包水型的皮克林乳液; 最后, 在紫外光的照射下引发香豆素侧基的交联反应从而得到“胶体体”微胶囊. 结果表明, 香豆素单体7-(2-甲基丙烯酰乙氧基)-4-甲基香豆素(CMA)和SiO2-PMMA-PCMA在紫外光作用下都可以发生交联反应, 以SiO2-PMMA- PCMA纳米粒子作乳化剂可以制备稳定的皮克林乳液, 光交联后得到的“胶体体”微胶囊的平均粒径约为170 μm. 相似文献
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原子转移自由基聚合及可控自由基聚合 总被引:11,自引:0,他引:11
以作者在原子转移自由基聚合领域的研究成果为主导,结合国内外文献,对近年来出现的颇具影响的可控自由基聚合体系与进行了评述与展望。 相似文献
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活性 (或称可控 )自由基聚合研究是目前高分子科学的研究热点之一[1~ 8] .活性自由基聚合制备的聚合物具有分子量随转化率提高而线性增加、分子量分布窄和聚合反应为一级反应动力学等特点 .自由基开环聚合所得产物体积收缩小 ,某些含有不饱和双键的螺环单体发生双开环聚合时甚至发生体积膨胀 ;开环聚合还可在聚合物主链上引入各种官能团 ,如酯基、碳酸酯基、酮基等 [9~ 12 ] .因此 ,用活性聚合的方法对自由基开环聚合的分子量和分子量分布进行控制 ,可以制备出具有各种不同结构和性能的新聚合物 . Wei等 [13] 报道了利用稳定自由基法实现… 相似文献
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Enrique Saldívar‐Guerra Jos Bonilla Fabiola Becerril Gregorio Zacahua Martha Albores‐Velasco Roberto Alexander‐Katz Leticia Flores‐Santos Larissa Alexandrova 《Macromolecular theory and simulations》2006,15(2):163-175
Summary: The range of validity of two popular versions of the nitroxide quasi‐equilibrium (NQE) approximation used in the theory of kinetics of alkoxyamine mediated styrene polymerization, are systematically tested by simulation comparing the approximate and exact solutions of the equations describing the system. The validity of the different versions of the NQE approximation is analyzed in terms of the relative magnitude of (dN/dt)/(dP/dt). The approximation with a rigorous NQE, kc[P][N] = kd[P N], where P, N and P N are living, nitroxide radicals and dormant species respectively, with kinetic constants kc and kd, is found valid only for small values of the equilibrium constant K (10−11–10−12 mol · L−1) and its validity is found to depend strongly of the value of K. On the other hand, the relaxed NQE approximation of Fischer and Fukuda, kc[P][N] = kd[P N]0 was found to be remarkably good up to values of K around 10−8 mol · L−1. This upper bound is numerically found to be 2–3 orders of magnitude smaller than the theoretical one given by Fischer. The relaxed NQE is a better one due to the fact that it never completely neglects dN/dt. It is found that the difference between these approximations lies essentially in the number of significant figures taken for the approximation; still this subtle difference results in dramatic changes in the predicted course of the reaction. Some results confirm previous findings, but a deeper understanding of the physico‐chemical phenomena and their mathematical representation and another viewpoint of the theory is offered. Additionally, experiments and simulations indicate that polymerization rate data alone are not reliable to estimate the value of K, as recently suggested.
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Cline Farcet Julien Nicolas Bernadette Charleux 《Journal of polymer science. Part A, Polymer chemistry》2002,40(24):4410-4420
The controlled free‐radical homopolymerization of n‐butyl acrylate was studied in aqueous miniemulsions at 112 and 125 °C with a low molar mass alkoxyamine unimolecular initiator and an acyclic β‐phosphonylated nitroxide mediator, N‐tert‐butyl‐N‐(1‐diethylphosphono‐2,2‐dimethylpropyl) nitroxide, also called SG1. The polymerizations led to stable latices with 20 wt % solids and were obtained with neither coagulation during synthesis nor destabilization over time. However, in contrast to latices obtained via classical free‐radical polymerization, the average particle size of the final latices was large, with broad particle size distributions. The initial [SG1]0/[alkoxyamine]0 molar ratio was shown to control the rate of polymerization. The fraction of SG1 released upon macroradical self‐termination was small with respect to the initial alkoxyamine concentration, indicating a very low fraction of dead chains. Average molar masses were controlled by the initial concentration of alkoxyamine and increased linearly with monomer conversion. The molar mass distribution was narrow, depending on the initial concentration of free nitroxide in the system. The initiator efficiency was lower than 1 at 112 °C but was very significantly improved when either a macroinitiator was used at 112 °C or the polymerization temperature was raised to 125 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4410–4420, 2002 相似文献
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Atom transfer radical polymerization (ATRP) was initially developed in the mid‐1990s, and with continued refinement and use has led to significant discoveries in new materials. However, metal contamination of the polymer product is an issue that has proven detrimental to widespread industrial application of ATRP. The laboratories of K. Matyjaszewski have made significant progress towards removing this impediment, leading the development of “activators regenerated by electron transfer” ATRP (ARGET ATRP) and electrochemically mediated ATRP (eATRP) technologies. These variants of ATRP allow polymers to be produced with great molecular weight and functionality control but at significantly reduced catalyst concentrations, typically at parts per million levels. This Concept examines these polymerizations in terms of their mechanism and outcomes, and is aimed at giving the reader an overview of recent developments in the field of ATRP. 相似文献
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Zhi Xu Shougen Yin Bin Lei Yan Lu Weixing Chang Jing Li 《Journal of polymer science. Part A, Polymer chemistry》2007,45(5):942-948
1,3‐dichloro‐tetra‐n‐butyl‐distannoxane, which contains Sn? Cl bonds, was used as a novel initiator for atom transfer radical polymerization of styrene in bulk. Some interesting results that were thought to be related to the characteristics of the 1,3‐dihalotetra‐alkyl‐distannoxanes had been obtained. The concentration of the 1,3‐dichlorotetra‐n‐butyl‐distannoxane in the bulk solution of styrene was confirmed to be an important factor for the different results of the polymerization. The corrected theoretical molecular weights, which were based on the proposed mechanism, accorded with the GPC results very well. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 942–948, 2007 相似文献