Raturi Parul, Singh J P
Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
Solid State Physics Laboratory, Lucknow Road, Timarpur, Delhi, 110054, India.
Sci Rep. 2018 Feb 27;8(1):3687. doi: 10.1038/s41598-018-21871-3.
Photomechanical actuation is the conversion of light energy into mechanical energy through some smart materials. Infrared-responsive smart materials have become an emerging field of research due to easy availability and eco-friendly nature of their stimulus in the form of sunlight, which contains about 50% of near-infrared(nIR) making these materials useful at macro-scale photoactuator applications. Here, we demonstrate fabrication of highly versatile nIR triggered photoactuators based on graphene oxide/polycarbonate bilayers that offers fast, low-cost fabrication, large deflection, reversible actuation and wavelength-selective response. The photoactuators are realized by vacuum filtration of graphene oxide/water dispersion through polycarbonate membrane resulting graphene oxide/polymer bilayer structure. The photoactuation response was measured in the form of deflection from equilibrium position as a result of infrared-irradiation. The deflection is caused by the generated thermal stress at the interface of bilayers due to mismatch of thermal expansion coefficient as a results of nIR absorption by graphene oxide and subsequent temperature rise. A maximum deflection of 12 mm (circular-shaped structure with diameter 28 mm) with corresponding bending curvature of 0.33 cm was shown by this photoactuator for illumination intensity of 106 mW/cm. Few applications of these photoactuators such as sunlight-driven smart curtain, infrared actuated curtain and self-folding box are also demonstrated.
光机械驱动是通过一些智能材料将光能转化为机械能。红外响应智能材料由于其刺激源（阳光）易于获取且环保，已成为一个新兴的研究领域。阳光中约含50%的近红外光（nIR），这使得这些材料在宏观尺度的光致动器应用中很有用。在此，我们展示了基于氧化石墨烯/聚碳酸酯双层的高度通用的近红外触发光致动器的制造方法，该方法具有快速、低成本制造、大挠度、可逆驱动和波长选择性响应等特点。这些光致动器是通过将氧化石墨烯/水分散体通过聚碳酸酯膜进行真空过滤，从而得到氧化石墨烯/聚合物双层结构来实现的。光驱动响应是以红外辐射导致的从平衡位置的挠度形式来测量的。这种挠度是由于氧化石墨烯吸收近红外光并随后温度升高，导致双层界面处因热膨胀系数不匹配而产生热应力所引起的。对于106 mW/cm的光照强度，该光致动器展示出最大挠度为12毫米（直径28毫米的圆形结构），相应的弯曲曲率为0.33厘米。还展示了这些光致动器的一些应用，如阳光驱动智能窗帘、红外驱动窗帘和自折叠盒。
