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通过改进的Hummers法制备了氧化石墨,在去离子水中超声处理得到纳米片层结构的GO。采用FT-IR、紫外可见吸收光谱和拉曼光谱对制备的氧化石墨的化学结构进行了表征。研究表明:通过氧化作用石墨的表面和层间生成了大量的含氧官能团,如羧基、羟基、环氧基等。SEM和AFM测试结果表明,所制得的GO不全是单层结构,而是由几个单片层叠加而成。GO的热稳定性由TGA进行测试,表面的含氧官能团在200~400℃分解,石墨烯骨架的分解在600℃以上,表明氧化石墨具有较好的热稳定性。选择GO和5CB为分散相,聚乙烯醇(PVA)为基体材料,通过溶液流延法制备PVA/5CB/GO复合薄膜。研究了液晶薄膜在可见光(450 nm)照射下的光致弯曲形变行为及机理。结果表明,利用GO的光热效应,将光能转换为热能,温度上升引发液晶发生了相变,导致复合薄膜表层收缩,发生快速的光致弯曲行为。形变的程度与薄膜中液晶的含量和拉伸率在一定范围内呈正比例关系。通过拉伸改善了液晶取向传统工艺(摩擦取向),降低了成本。
Graphite oxide was prepared by the modified Hummers method and the nanosheet structure GO was obtained by sonication in deionized water. The chemical structure of the prepared graphite oxide was characterized by FT-IR, UV-Vis absorption spectra and Raman spectroscopy. The results show that a large number of oxygen-containing functional groups such as carboxyl, hydroxyl, epoxy and the like are formed on the surface and interlayer of graphite by oxidation. SEM and AFM test results show that the prepared GO is not a single layer structure, but by a few monolithic stack. The thermal stability of GO was tested by TGA. The oxygen functional groups on the surface decomposed at 200-400 ℃ and the decomposition of graphene skeleton was above 600 ℃, indicating that graphite oxide has good thermal stability. GO and 5CB were selected as disperse phase and polyvinyl alcohol (PVA) as matrix material. PVA / 5CB / GO composite films were prepared by solution casting. The photodisplastic deformation behavior and mechanism of liquid crystal thin film under visible light (450 nm) irradiation were studied. The results show that the use of GO photothermal effect, the light energy is converted to heat, the temperature rise caused the liquid crystal phase change, resulting in shrinkage of the composite film surface, rapid photo-induced bending behavior. The degree of deformation is proportional to the content of liquid crystal and the elongation in the film within a certain range. The traditional process of liquid crystal alignment (rubbing alignment) is improved by stretching, reducing the cost.