Introduction of pH-Sensitivity into Mechanically Strong Nanoclay Composite Hydrogels Based on N-Isopropylacrylamide.
Introduction of pH-Sensitivity into Mechanically Strong Nanoclay Composite Hydrogels Based on N-Isopropylacrylamide.
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DOI：
10.1002/pola.22973
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发表时间：
2008-10-01
影响因子：
--
通讯作者：
Siegel, Ronald A.
中科院分区：
文献类型：
--
作者：
Mujumdar, Siddharthya K.;Siegel, Ronald A.
以N-异丙基丙烯酰胺（NIPA）为单体，分别与阳离子单体和阴离子单体共聚，制备了pH敏感性纳米粘土复合水凝胶。Laponite纳米粘土颗粒充当多功能交联剂，产生具有异常高的机械强度的水凝胶，如通过断裂伸长率测量的。采用Haraguchi（Adv Mater 2002，14，1120-1124）报道的方法，通过水性自由基聚合制备基于NIPA和甲基丙烯酸二甲氨基乙酯的阳离子共聚物凝胶。在没有修改的情况下，由于粘土颗粒的絮凝，该技术未能产生NIPA和甲基丙烯酸的阴离子共聚物凝胶。设想了三种方法将酸性MAA掺入纳米粘土水凝胶中。首先，NIPA在稀条件下与酸性共聚单体共聚，产生具有良好pH敏感性但弱机械特性的水凝胶。其次，NIPA与甲基丙烯酸甲酯共聚，然后水解产生酸侧基，产生更强但pH敏感性更低的水凝胶。第三，NIPA与酸共聚单体共聚后，用焦磷酸根离子修饰纳米粘土表面。所得水凝胶在37 °C下表现出强的pH敏感性和优异的拉伸性能。光学透明度在聚合期间改变，这取决于组分的疏水性。这项工作增加了纳米粘土水凝胶的多样性和功能性，与传统交联水凝胶相比，纳米粘土水凝胶显示出一定的机械优势。
pH-sensitive nanoclay composite hydrogels based on N-isopropylacrylamide (NIPA) were synthesized by copolymerization with cationic and anionic comonomers. Laponite nanoclay particles served as multifunctional crosslinkers, producing hydrogels with exceptionally high mechanical strengths, as measured by elongation at break. Cationic copolymer gels based on NIPA and dimethylaminoethylmethacrylate were prepared by aqueous free radical polymerization, adopting a procedure reported by Haraguchi (Adv Mater 2002, 14, 1120–1124). Without modification, this technique failed to produce anionic copolymer gels of NIPA and methacrylic acid due to flocculation of clay particles. Three methods were conceived to incorporate acidic MAA into nanoclay hydrogels. First, NIPA was copolymerized with acidic comonomer under dilute conditions, producing hydrogels with good pH-sensitivity but weak mechanical characteristics. Second, NIPA was copolymerized with methyl methacrylate, which was then hydrolyzed to generate acid sidegroups, yielding hydrogels that were much stronger but less pH sensitive. Third, NIPA was copolymerized with an acid comonomer following modification of the nanoclay surface with pyrophosphate ions. The resulting hydrogels exhibited both strong pH-sensitivities at 37 °C and excellent tensile properties. Optical transparency changed during polymerization, depending on hydrophobicity of the components. This work increases the diversity and functionality of nanoclay hydrogels, which display certain mechanical advantages over conventionally crosslinked hydrogels.
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影响因子：
16.6
作者：
Haraguchi, K;Li, HJ
通讯作者：
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8.6
作者：
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作者：
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作者：
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作者：
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