Nanocomposite Gels by Initiator-Free Photopolymerization: Role of Plasma-Treated Clay in the Synthesis and Network Formation
Nanocomposite Gels by Initiator-Free Photopolymerization: Role of Plasma-Treated Clay in the Synthesis and Network Formation
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DOI：
10.1021/acsanm.7b00264
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发表时间：
2018-01-01
影响因子：
5.9
通讯作者：
Haraguchi, Ryosuke
中科院分区：
文献类型：
--
作者：
Haraguchi, Kazutoshi;Takada, Tetsuo;Haraguchi, Ryosuke
采用等离子体处理粘土，在水介质中通过无引发剂光聚合成功合成了由聚合物-粘土网络构成的纳米复合水凝胶。IF-NC凝胶具有高的拉伸强度，断裂应变，和热响应性，这是几乎相同的NC凝胶制备的氧化还原和光引发剂的方法，通过优化等离子体处理条件和剥离在水中。粘土纳米片作为引发剂、多功能交联剂和助剂在促进原位自由基聚合成IF-NC凝胶中发挥重要作用。在IF-NC凝胶中的聚合物粘土网络的形成的机制是澄清通过傅立叶变换红外和电子自旋共振研究，并涉及通过等离子体处理和随后的紫外线照射，分别在粘土表面上形成氢过氧化物和自由基，并通过设计的自由基聚合实验中存在或不存在的粘土纳米片。由于其简单和多功能的合成，形式和大小的多样性，以及极好的特性，IF-NC凝胶可用于各种应用。这些结果为超级水凝胶和有机-无机纳米复合材料以及聚合物合成和光化学提供了重要的见解。
Nanocomposite hydrogels (NC gels) composed of polymer-clay networks are successfully synthesized via initiator-free (IF) photopolymerization in aqueous media using plasma-treated clay. IF-NC gels with a high tensile strength, strain at break, and thermoresponsiveness, which are almost identical to those of NC gels prepared by redox and photoinitiator methods, are obtained by optimizing the plasma-treatment conditions and exfoliation in water. The clay nanosheets play important roles as initiators, multifunctional cross-linkers, and auxiliary agents for facilitating in situ free-radical polymerization toward IF-NC gels. The mechanism for the formation of the polymer clay network in the IF-NC gels is clarified through Fourier transform infrared and electron spin resonance studies and involves the formation of hydroperoxides and radicals on the clay surface by plasma treatment and subsequent UV irradiation, respectively, and through designed free-radical polymerization experiments in the presence or absence of the clay nanosheets. Because of their simple and versatile syntheses, form and size diversities, and superb characteristics, IF-NC gels can be used in a variety of applications. The results provide important insight into super-hydrogels and organic-inorganic nanocomposites, as well as polymer synthesis and photochemistry.