Infrared-driving actuation based on bilayer graphene oxide-poly(N-isopropylacrylamide) nanocomposite hydrogels
Infrared-driving actuation based on bilayer graphene oxide-poly(N-isopropylacrylamide) nanocomposite hydrogels
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DOI：
10.1039/c4ta02866j
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发表时间：
2014-08
影响因子：
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通讯作者：
Enzhong Zhang;Tao Wang;Wei Hong;Weixiang Sun;Xinxing Liu;Zhen Tong
中科院分区：
文献类型：
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作者：
Enzhong Zhang;Tao Wang;Wei Hong;Weixiang Sun;Xinxing Liu;Zhen Tong
刺激响应性水凝胶被用作致动器中的智能材料，用于将外部刺激转化为致动运动。红外辐射由于可以穿透生物材料而不直接接触，并且可以远程控制，被认为是一种理想的驱动能量。在本工作中，一种新的红外驱动双层水凝胶驱动器的制备通过堆叠的氧化石墨烯（GO）-锂蒙脱石粘土-聚（N-异丙基丙烯酰胺）（PNIPAm）凝胶层上的锂蒙脱石粘土-PNIPAm凝胶层，通过逐步原位聚合合成。凝胶中的GO吸收IR辐射并快速有效地将其转化为热能，导致含GO的凝胶层中的温度比不含GO的凝胶层中的温度更快地升高，并且前者的温度变得高于后者的温度。这种具有不同温度的双层结构将各向同性体积收缩改变为各向异性变形，即，弯曲，其总是朝向含GO层。此外，由于坚韧凝胶的自支撑能力，这种弯曲在大气中发生。通过打开和关闭IR光来实现弯曲恢复的重复。根据这些观察，具有GO的双层凝胶为新的软致动器提供了坚韧的IR驱动材料。
Stimulus-responsive hydrogels are utilized as smart materials in actuators for transforming external stimuli into actuation movements. Infrared (IR) irradiation is considered to be an ideal driving energy because it can penetrate into biomaterials without direct contact and can be remotely controlled. In the present work, a new IR-driving bilayer hydrogel actuator is prepared by stacking a graphene oxide (GO)-hectorite clay-poly(N-isopropylacrylamide) (PNIPAm) gel layer onto a hectorite clay-PNIPAm gel layer, synthesized through stepwise in situ polymerization. GO in the gel absorbs the IR irradiation and rapidly and efficiently transforms it into thermal energy, resulting in a much faster temperature increase in the GO-containing gel layer than that of the gel layer without GO, and the temperature of the former becomes higher than that of the latter. This bilayer structure with different temperatures changes the isotropic volume contraction into an anisotropic deformation, i.e., bending, which is always toward the GO-containing layer. Moreover, this bending occurs in the atmosphere, owing to the self-supporting capability of the tough gels. The repetition of the bending recovery is realized by turning the IR light on and off. According to these observations, the bilayer gel with GO provides a tough and IR-driving material for new soft actuators.