纤维素/石墨烯/离子液体溶液流变行为与其复合膜再生结构及性能关系研究

Ionic liquid is a new and highly efficient green solvent for dissolving cellulose. But, the application of ionic liquid in polymer nanocomposites is limited for the difficulties in dispersing nanoparticles and dissolving polymer, due to its high viscosity. In our previous work, it was found that the concentration of graphene dispersed in ionic liquid could be increased while the viscosity of the liquid mixture was largely decreased, in which the graphene was obtained via direct exfoliation of nature graphite with the aid of a small amount of cellulose in ionic liquid. In this project, the effect of contents of cellulose and graphene sheets on the rheological behavior of ionic liquid will be studied systematically, and the mechanism of reducing the viscosity of ionic liquid through the synergistic effect of the small amount of cellulose and graphene will be explored. Based on those, effect of the regeneration technologies on the self-assembled network structure of cellulose and dispersibility of graphene sheets in cellulose/graphene membranes will be also investigated. Meanwhile, the fabrication methods of cellulose/graphene membranes with high performance in transparency and conductivity will be explored. With these researches as basis, the relationship between the rheological behavior of cellulose/graphene/ionic liquid solutions, regeneration technologies and the structure-properties of cellulose/graphene membranes will be established, which will provide theoretical reference for the development and application of transparent and conductive cellulose/graphene membranes.

作为一种新型高效的绿色溶剂，离子液体可直接快速的溶解纤维素，但离子液体粘度大的特性不利于高分子或纳米粒子在其中的有效分散，从而限制了它在高分子纳米复合材料制备中的应用。我们前期的初步研究发现，少量纤维素的加入可大大提高离子液体直接剥离石墨制备石墨烯的产率，同时极大地降低所得石墨烯/离子液体溶液的粘度。本项目拟系统地考察微量纤维素及石墨烯含量对离子液体流变行为的影响，并阐明其两者协同作用降低离子液体粘度的机理。在此基础上，进一步研究再生成膜工艺对所制备的纤维素/石墨烯复合膜中纤维素自组装网络结构及石墨烯在其中分散性的影响，探索高性能透明导电纤维素/石墨烯复合膜的制备方法。通过以上研究，建立纤维素/石墨烯/离子液体复合溶液的流变行为、再生工艺与所得纤维素/石墨烯复合膜结构与性能关系，为透明导电纤维素/石墨烯复合膜的研发及应用提供理论指导。

作为一种新型高效的绿色溶剂，离子液体可直接快速的溶解纤维素，但离子液体粘度大的特性不利于高分子或纳米粒子在其中的有效分散，从而限制了它在高分子纳米复合材料制备中的应用。我们前期的初步研究发现，少量纤维素的加入可大大提高离子液体直接剥离石墨制备石墨烯的产率，同时极大地降低所得石墨烯/离子液体溶液的粘度。在此基础上，我们系统地考察了纤维素及石墨烯含量对离子液体流变行为的影响，根据实验结果及文献调研，我们提出两者协同作用降低离子液体粘度的机理为纤维素分子及石墨烯片能够有效破坏离子液体阴阳离子间的离子键，该结论还需进一步理论推导。进而，我们调控再生温度，考察所制备的纯纤维素及纤维素/石墨烯复合膜中纤维素自组装网络结构及石墨烯对复合膜性能的影响；除此之外，我们还基于石墨和纤维素为原料制备了兼具增强增韧的透明导电纤维素/石墨烯复合膜，超低密度且高弹耐疲劳的石墨烯气凝胶以及具有韧性、表面为玫瑰花瓣可吸附水的石墨烯/天然胶乳杂化气凝胶。通过上述研究，我们成功建立了纤维素/石墨烯/离子液体复合溶液的流变行为、再生工艺与所得纤维素/石墨烯复合膜结构与性能关系，为纤维素/石墨烯复合膜的研发及应用提供理论指导。