Janus microgels prepared by surfactant-free pickering emulsion-based modification and their self-assembly
Janus microgels prepared by surfactant-free pickering emulsion-based modification and their self-assembly
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DOI：
10.1021/ja072258w
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发表时间：
2007-07-04
影响因子：
15
通讯作者：
Kawaguchi, Haruma
中科院分区：
文献类型：
--
作者：
Suzuki, Daisuke;Tsuji, Sakiko;Kawaguchi, Haruma
我们目前的Janus微凝胶使用皮克林乳液为基础的方法修改，并证明他们的自组装。采用水相自由基沉淀聚合法合成了由交联聚[N-异丙基丙烯酰胺-co-（丙烯酸）]（pNA）组成的刺激响应性微凝胶。使用pNA微凝胶作为稳定剂，通过与pNA分散体和十六烷的简单搅拌形成Pickering乳液。然后通过使用乙二胺和1-乙基-3-（3-二甲基氨基丙基）碳二亚胺的碳二亚胺偶联反应引入氨基。这些微凝胶通过乳液塌陷收集。利用Au纳米粒子标记技术证实了改性微凝胶中氨基的半球形分布。有趣的是，这些微凝胶在pH 4时聚集成弦结构，而在pH 6时则不是。这种由结构良好的微凝胶通过简单的刺激变化自组装而成的微凝胶串结构具有作为微致动器的潜在用途。
We present Janus microgels modified using a Pickering emulsion-based approach and demonstrate their self-assembly. Stimuli-responsive microgels composed of cross-linked poly[N-isopropylacrylamide-co-(acrylic acid)] (pNA) were synthesized by means of aqueous free-radical precipitation polymerization. Using pNA microgels as stabilizers, a Pickering emulsion was formed by simple stirring with pNA dispersion and hexadecane. The amino groups were then introduced by means of a carbodiimide coupling reaction using ethylenediamine and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. These microgels were collected by emulsion collapse. Hemispherical distribution of the amino groups in the modified microgels was confirmed using the Au nanoparticle labeling technique. Interestingly, these microgels were aggregated in string structures at pH 4, whereas they were not at pH 6. Such microgel string structures self-assembled from well-structured microgels by simple stimuli-change have potential use as micro-actuators.