羧基化纳米MoS2/PLA复合材料设计、制备及光电响应性研究

The traditional materials with photoelectric responses are almost inorganic semiconductors. They are hard to be processed and cannot meet the requirements of complicated electron devices. More importantly, the increased wastes of these materials put a huge pressure on the environment. Therefore, in this project, we aim to composite nano molybdenum disulfide (MoS2) with polylactic acid (PLA) to explore environment-friendly materials with photoelectric responses. MoS2 is a kind of layered nanomaterial with quick photoelectric responses, and PLA is an easily-obtained degradable polymer. In order to improve the rate of photoelectric responses for MoS2 as well as the compatibility for PLA and MoS2, the layered nano MoS2 will be modified by mercaptoacetic acid firstly to form COOH-MoS2. Then the COOH-MoS2 will be composite with PLA through the direct solution blend or in situ ring-opening polymerization methods. Through the solution blend method, homogeneous nanocomposites will be obtained with the help of the hydrogen bonds between COOH-MoS2 and PLA, while by the in situ ring-opening polymerization, the PLA chains coming from the polymerization of lactide can graft onto the COOH-MoS2 to from homogeneous nanocomposites. The photoelectric responses of the result nanocomposites will be fully studied by the analysis of electric signal vs the applied voltage, light intensity or wavelength of the light. Relationship between the micro structures and macro properties of the nanocomposites will also be examined. This can be very helpful for the exploration of other environment-friendly materials with photoelectric responses.

传统光电响应性材料多属不可降解的无机半导体材料，加工困难，难以满足复杂电子元器件的使用要求，且大量废弃电子产品带来了严重的环境污染。本项目拟以具有高响应速度、高转化效率的光电响应性纳米二硫化钼（MoS2）与原料易得的可生物降解聚乳酸（PLA）复合，制备环保型光电响应性材料。为提高纳米MoS2的光电响应性及其与PLA的相容性，拟以巯基乙酸对其改性，获得高羧基含量的羧基化MoS2片层纳米材料，并采用溶液复合（依据羧基化MoS2与PLA分子形成氢键相互作用）和原位聚合（利用丙交酯开环后可与MoS2表面羧基反应，将分子链接枝到MoS2上）两种方式制备MoS2/PLA纳米复合材料。以材料电信号随外加电压、光强及波长的变化关系为着眼点研究复合材料的光电响应特性，掌握复合材料微观结构对其光电响应性及热力学性能的影响规律，为环境友好型光电功能聚合物纳米复合材料的设计及机理研究进行科学探索。

二硫化钼是一种具有可见光响应的层状纳米材料，在聚合物改性和光电纳米材料领域具有广泛的应用前景，对二硫化钼的制备、功能化及应用研究具有重要意义。本项目分别采用了锂离子插层法和高分子辅助机械剥离法制备了层状纳米二硫化钼，并对其进行了羧基化和氨基化修饰，所获的功能化的纳米二硫化钼与聚合物基体相容性好。分别采用不同方法将修饰后的纳米二硫化钼引入了一系列聚合物中，制备了多种性能显著提升的聚合物纳米复合材料。采用原位开环聚合反应法制备了聚乳酸/二硫化钼复合材料，复合材料的力学和热学性能提高。当MoS2含量为0.5 wt%时，聚乳酸在80℃时的储能模量提高了一个数量级，其抵抗热变形的能力显著提升。采用原位聚合反应制备了多孔的温度响应型羟丙基纤维素（HPC）与羧基化纳米二硫化钼的复合水凝胶，复合水凝胶不仅对污染物具有优异的吸附性能，还具有光致可回收性能。采用海藻酸钠（SA）辅助液相剥离法制备功能化的MoS2（SA- MoS2），通过超声的方法在MoS2表面粘附大量的羟基和羧基等亲水性的官能团。通过溶液共混法制备SA/SA- MoS2复合材料。由于SA与SA- MoS2具有良好的相容性，所成复合材料厚度均一，颜色具有规律性。填料的含量为0.5%时，复合材料的力学性能提高了一个数量级以上。这些研究丰富了纳米二硫化钼的制备和表面修饰方法，并对提高其在聚合物基体中的分散和对高分子的性能改善方面做了一系列有益的探索，可为纳米二硫化钼在高分子改性领域的应用提供一定的指导。