Ying Zhimin, Lin Xiao Ying, Du Cong, Zheng Si Yu, Wu Zi Liang, Zheng Qiang
Second Affiliated Hospital, School of Medicine, Zhejiang University Hangzhou 310009 China.
Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University Hangzhou 310027 China
RSC Adv. 2019 Sep 13;9(49):28876-28885. doi: 10.1039/c9ra04558a. eCollection 2019 Sep 9.
Anisotropic nanocomposite films of hydroxypropylcellulose (HPC) and graphene oxide (GO) were fabricated by blade-coating of the aqueous mixture to align the substance and subsequent solvent evaporation to freeze the oriented structure. Owing to the anisotropic structure, the composite films showed anisotropic mechanical properties and response to external stimuli. The influences of GO content, stretch rate, and relative humidity on the anisotropic structure and mechanical properties of the films were investigated. The incorporation of GO did not destroy the anisotropic structure of the HPC film, but improved the mechanical properties to some extent and favoured the bending deformation and locomotion of the composite film under the humidity gradient. These behaviours were associated with the large aspect ratio and excellent gas barrier property of GO nanosheets that favoured suppressing the slippage of HPC chains and enhanced the differential volume change at the top and bottom surfaces of the film. The composite HPC film with GO or reduced GO also responded to near-infrared light due to the photothermal effect and the variation of HPC matrix at a high temperature. This facile strategy should be applicable to other natural or synthetic polymers to fabricate anisotropic composite films with potential applications as optical devices, sensors, and actuators.
通过刮涂羟丙基纤维素（HPC）和氧化石墨烯（GO）的水性混合物来制备各向异性的纳米复合薄膜，以使物质排列，随后通过溶剂蒸发来固定取向结构。由于具有各向异性结构，复合薄膜表现出各向异性的机械性能以及对外部刺激的响应。研究了GO含量、拉伸速率和相对湿度对薄膜各向异性结构和机械性能的影响。GO的加入并未破坏HPC薄膜的各向异性结构，而是在一定程度上改善了机械性能，并有利于复合薄膜在湿度梯度下的弯曲变形和移动。这些行为与GO纳米片的大长径比和优异的气体阻隔性能有关，这有利于抑制HPC链的滑动，并增强薄膜上下表面的体积差异变化。含有GO或还原GO的复合HPC薄膜由于光热效应以及高温下HPC基体的变化，也对近红外光有响应。这种简便的策略应适用于其他天然或合成聚合物，以制备具有潜在应用价值的各向异性复合薄膜，如光学器件、传感器和致动器。
