原子转移自由基聚合
高分子化学
凝胶渗透色谱法
共聚物
聚合物
摩尔质量分布
材料科学
丙烯酸酯
丙烯酸丁酯
环糊精
化学
有机化学
复合材料
作者
Paweł Chmielarz,Sangwoo Park,Andrzej Sobkowiak,Krzysztof Matyjaszewski
出处
期刊:Polymer
[Elsevier]
日期:2016-04-01
卷期号:88: 36-42
被引量:63
标识
DOI:10.1016/j.polymer.2016.02.021
摘要
Cyclodextrin-based star polymers were synthesized using functionalized β-cyclodextrin (β-CD) core, and n-butyl acrylate (BA) as hydrophobic arms. The β-CD core macroinitiator was prepared by the transesterification reaction of β-CD with 2-bromoisobutyryl bromide. The core-first method was chosen as the synthetic strategy as it allows good control over the polymer architecture. Star-shaped amphiphilic polymers were prepared via a simplified electrochemically mediated ATRP (seATRP) procedure under both potentiostatic and pseudo-galvanostatic conditions, utilizing only 50 ppm (40 ppm by weight (wt)) of CuII complex, much less than previously reported concentrations of catalyst of ca. 4,000–130,000 ppm (590–19,000 ppm (by wt)). The rate of the polymerizations (Rp) was controlled by applying different potentials Eapp, with slower Rp observed using more positive Eapp values thereby suppressing intermolecular termination reactions between growing arms, and subsequent star–star coupling. The polymerization results showed molecular weight evolution close to theoretical values while maintaining a narrow molecular weight distribution for the growing star polymer throughout the reaction. The differences between theoretical and measured MW originate in different hydrodynamic radii of stars and linear polymers used as standards for gel-permeation chromatography (GPC). Successful chain extension of the ω-functional arms with tert-butyl acrylate (tBA) resulted in star block copolymers and confirmed the living nature of the β-CD-PBA star polymers prepared by seATRP. Moreover, the absence of radical coupling reactions during seATRP synthesis was confirmed by GPC analyses of the actual arm length of obtained star polymers and copolymers.
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