We investigated the adhesion behavior of nanocomposite hydrogels (NC gels), consisting of unique organic (polymer)–inorganic (clay) network structures, toward inorganic and organic materials. The NC gels exhibit instant and strong adhesion to inorganic and organic substrates with hydrophilic porous surfaces. The NC gels instantly adhere to hydrophilic porous substrates (e.g., unglazed ceramic surfaces and polymer membranes) through simple light contact. In addition, a small piece of NC gel effectively joined two substrate samples (e.g., concrete blocks and bricks) through lamination of the interposing NC gel. The resulting conjoined materials were unable to be separated at the gel–substrate interface; rather, the gel itself fractured upon separation, which indicates that the adhesive strength at the interface is greater than the tensile strength of the NC gel. With the exception of NC gels with very high clay concentrations (C_clay’s), instant strong adhesion and cohesive failure by subsequent stretching were observed for almost all NC gels composed of different polymers or different C_clay values. A thermoresponsive NC gel was reversibly adhered and could be peeled from the surface by stretching (adhesive failure) at a temperature above its transition temperature. The mechanism of instant strong adhesion or reversible adhesion is discussed based on dangling chains that exist on the surfaces of the NC gels composed of polymer–clay networks. The cut surface of an NC gel generally exhibited a higher adhesive strength than the as-prepared surface because of longer dangling chains.

中文翻译：

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纳米复合凝胶对亲水性多孔材料的即时强粘合行为

我们研究了由独特的有机（聚合物）-无机（粘土）网络结构组成的纳米复合水凝胶（NC凝胶）对无机和有机材料的粘附行为。NC凝胶对具有亲水性多孔表面的无机和有机基材表现出即时而牢固的粘合力。NC凝胶通过简单的光接触即刻粘附到亲水性多孔基材（例如，未上釉的陶瓷表面和聚合物膜）上。另外，一小片NC凝胶通过层压插入的NC凝胶有效地连接了两个基材样品（例如，混凝土块和砖头）。产生的结合材料无法在凝胶-底物界面分离。相反，凝胶本身在分离时会破裂，这表明界面处的粘合强度大于NC凝胶的拉伸强度。除具有极高粘土浓度的NC凝胶外（C_粘土），几乎所有由不同聚合物或不同C_粘土值组成的NC凝胶都观察到了由于随后的拉伸而引起的即时强粘合力和内聚破坏。热响应性NC凝胶可逆地粘附，并可以在高于其转变温度的温度下通过拉伸（粘附破坏）从表面上剥离。基于存在于聚合物-粘土网络的NC凝胶表面上存在的悬空链，讨论了即时强粘附或可逆粘附的机制。由于较长的悬挂链，NC凝胶的切割表面通常比准备好的表面具有更高的粘合强度。