具有高湿敏性和机械强度的还原氧化石墨烯/醋酸纤维素湿敏膜的可控制备及性能研究

Reduced graphene oxide (rGO) has broad application prospects in the field of precision humidity detection due to its unique properties, and has received extensive attention. However, due to the low content of oxygen-containing groups and the curling and deposition of the rGO sheet structure, the mechanical properties and humidity sensitivity of the rGO humidity sensitive film are poor, which limits its application prospects. This study focuses on the preparation of high strength and humidity sensitive rGO based humidity sensitive films. Design and synthesis of low-substituted cellulose acetate (WSCA) with high degree of polymerization and good solubility by utilizing the designability and weak reactivity of the anhydride structure. Using the amphiphilic and abundant hydroxyl groups of WSCA molecular structure to solve the problem of poor strength and humidity sensitivity of rGO sheets. High-strength rGO/WSCA humidity sensitive film with ordered 'brick-mud' structure was formed by regulating the hydrogen bonds between WSCA and rGO. In addition, the relationship between the WSCA molecular structure and the microstructure of the humidity sensitive film on the humidity sensitivity and mechanical properties were elucidated, and the key factors for obtaining humidity sensitive film with excellent microstructure, humidity sensitivity and mechanical properties were obtained. Controllable preparation of reduced graphene oxide/cellulose acetate humidity-sensitive films with high mechanical strength and humidity sensitivity, and provides a theoretical basis for the development of rGO based humidity sensitive films and the utilization of biomass resource.

还原氧化石墨烯(rGO)因其独特的结构，使以其为原料制得的湿敏膜在精密湿度检测领域具有广泛的应用前景，成为当今的研究热点。然而，rGO含氧基团较少且片层结构易卷曲沉积，使得rGO湿敏膜机械性能和湿敏性能均不是很理想，限制了其应用前景。本课题围绕制备高强度和湿敏性rGO湿敏膜为主要目标，利用酸酐结构可设计性和弱反应活性设计合成聚合度高水溶性好的低取代醋酸纤维素（WSCA），利用WSCA分子结构的双亲性及丰富的羟基，解决rGO湿敏性差且片层结构易卷曲沉积的问题。通过对WSCA与rGO之间氢键等分子间作用力的调控，自组装形成有序“砖-泥”结构高强度rGO/WSCA湿敏膜。阐明WSCA分子结构和湿敏膜微观结构对湿敏性能和力学性能影响规律，得到获得微观结构有序、湿敏和力学性能优良湿敏膜的关键因素，实现兼顾强度和湿敏性rGO/WSCA湿敏膜的可控制备，为rGO湿敏膜发展及生物质高值化利用提供理论基础。

湿度传感器与我们息息相关，湿敏材料是决定其性能的关键因素。近年来，还原氧化石墨烯(rGO)湿敏材料受到广泛关注，但纯rGO湿敏膜存在机械强度差不能独立支撑，且湿敏性差的问题。本项目围绕制备兼顾强度和湿敏性rGO湿敏膜为主要目标，提出将rGO与亲水生物质大分子纤维素结合。利用离子液体和酰氯的反应设计酸酐结构，来调节纤维素葡萄糖单元中不同C-羟基的取代顺序和比例，最大程度保留纤维素结构中的羟基，合成适宜与rGO复合的低取代、高聚合度的水溶性醋酸纤维素（WSCA）。利用WSCA的高机械强度和丰富的亲水羟基来提高rGO膜的强度和湿敏性能。在此基础上，设计合成不同结构的WSCA，优选出有效提高复合膜湿敏性能的WSCA，明确WSCA化学结构和复合膜湿敏性能之间的本质规律及作用机制，揭示复合膜湿度敏感机理，并以湿敏机理为理论指导，实现高性能湿敏复合膜的可控构建，并提供一种生物质资源高值化利用的新途径。