Preparation of gradient copolymers via ATRP in miniemulsion. II. Forced gradient
Preparation of gradient copolymers via ATRP in miniemulsion. II. Forced gradient
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DOI：
10.1002/pola.21911
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发表时间：
2007-04
期刊：
影响因子：
--
通讯作者：
K. Min;J. Oh;K. Matyjaszewski
中科院分区：
文献类型：
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作者：
K. Min;J. Oh;K. Matyjaszewski
通过细乳液中的原子转移自由基聚合成功制备了一系列沿共聚物主链具有不同受控单体单元分布的强制梯度共聚物。新开发的引发技术，称为通过电子转移产生的活化剂，有利于强制梯度共聚物的制备，因为所有聚合物链都是在细乳液液滴内引发的，并且细乳液在整个聚合过程中保持稳定。本研究检查了具有不同反应活性比的各种单体对，包括丙烯酸正丁酯/丙烯酸叔丁酯、甲基丙烯酸正丁酯/甲基丙烯酸甲酯和丙烯酸正丁酯/苯乙烯。在每种情况下，添加的单体扩散穿过水悬浮介质，并获得沿聚合物主链具有不同强制分布的共聚单体单元的梯度共聚物。沿着共聚物主链的梯度形状受到单体的摩尔比、共聚单体的反应性比以及进料速率的影响。梯度的形状也受到共聚单体的相对疏水性的影响。共聚对所有进料速率和共聚单体进料比均表现出良好的控制，窄分子量分布（Mw/Mn = 1.20–1.40）和分子量随聚合物产率平稳增加证明了这一点，表明引发效率高。 © 2006 Wiley periodicals, Inc. J Polym Sci Part A：Polym Chem 45：1413–1423，2007
A series of forced gradient copolymers with different controlled distribution of monomer units along the copolymer backbone were successfully prepared by atom transfer radical polymerization in miniemulsion. The newly developed initiation technique, known as activators generated by electron transfer, was beneficial for forced gradient copolymers preparation because all polymer chains were initiated within the miniemulsion droplets and the miniemulsion remained stable throughout the entire polymerization. Various monomer pairs with different reactivity ratios were examined in this study, including n-butyl acrylate/t-butyl acrylate, n-butyl methacrylate/methyl methacrylate, and n-butyl acrylate/styrene. In each case, the added monomer diffused across the aqueous suspending medium and gradient copolymers with different forced distributions of comonomer units along the polymer backbone were obtained. The shape of the gradient along the backbone of the copolymers was influenced by the molar ratio of the monomers, the reactivity ratio of the comonomers as well as the feeding rate. The shape of the gradient was also affected by the relative hydrophobicities of the comonomers. Copolymerizations exhibited good control for all feeding rates and comonomer feeding ratios, as evidenced by narrow molecular weight distribution (Mw/Mn = 1.20–1.40) and molecular weight increasing smoothly with polymer yield, indicating high initiation efficiency. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1413–1423, 2007