纤维素基气凝胶的结构调控及其高性能化的基础研究

Cellulose is the most abundant renewable biomass resource, and possesses environmental benefits and excellent physical and mechanical properties. As highly porous materials with nano-sized open pores, cellulose-based aerogels have further combined the characters of high porosities, low densities and high specific surface areas of aerogels. Therefore, cellulose-based aerogels are very promising materials in many application fields. This project is proposed in the potential application to use cellulose-based aerogels as transparent heat-insulation materials based on the investigation of their preparation, structures and properties. The various processes in the preparation of cellulose-based aerogels would be studied, including cellulose dissolution in non-derivatizing solvents, cellulose blending and compounding with strengthen agents, cellulose regeneration by coagulation baths, solvent exchange with anhydrous organic solvents and drying in supercritical CO2. Accordingly, an insight would be obtained into the factors to influence the gelation of cellulose solution, which determines the final properties of aerogels. The synergetic modulation in multi-scale architectures of cellulose-based aerogels, consisting of cellulose molecular structure, condensed state and porous structure, would result in the optimization of the three dimensional nano-sized porous network in the aerogels. On the other hand, the strengthen effect in the matrix could be introduced from well dispersed nano-sized filler or a second polymer having strong interaction with cellulose. Consequently, the optical transmission, heat-insulation property and mechanical strength of cellulose-based aerogels would be improved. The results obtained in this project would be not only to improve the understanding of the inner relationship of preparation - multiscale architecture - service performances of cellulose-based aerogels from a fundamental point of view, but also of the technological importance to extend the property ranges of cellulose-based aerogels and provide solid foundation for the research and development of high performance cellulose-based aerogels.

纤维素基气凝胶是一种含有大量纳米级开放孔洞的多孔材料，兼具气凝胶材料的高孔率、低密度和高比表面积等特性，和纤维素的储量大、可再生、环境友好和良好的物理力学性能等优点，在诸多领域有着很好的应用前景。本申请针对纤维素基气凝胶作为透明隔热材料的潜在应用，拟对纤维素基气凝胶的制备、结构和性能开展研究，分别从气凝胶制备中的纤维素溶解、共混复合、再生以及溶剂交换和超临界CO2干燥等方面入手，对决定气凝胶最终性能的纤维素溶液凝胶化环节，认识其影响因素；从纤维素分子结构、聚集态结构及孔结构等多尺度结构上协同作用，在获得良好的三维纳米多孔网络结构基础上，引入纳米填料和强相互作用对基体进行增强，进而提高纤维素基气凝胶的光透过率、隔热性能和强度等物理力学性能。理论上，深化对纤维素基气凝胶的制备-多尺度结构-使用性能内在关系的认识；应用上，拓展纤维素基气凝胶的性能范围，为高性能材料的开发和应用提供研究基础。

纤维素基气凝胶是一种兼具气凝胶材料的超轻、高孔率、高比表面积等特性，和纤维素材料的来源丰富、可再生、可生物降解、成型性好等优点的新型多孔材料，在诸多领域有着很好的应用前景，近年来吸引了研究者越来越多的关注。本项目以绿色、环保、可重复使用的1-烯丙基甲基咪唑氯盐离子液体（AmimCl）为纤维素溶剂，首先对纤维素溶液的凝胶化过程、及其对纤维素气凝胶的孔结构的调控和材料性能的影响进行研究，获得了制备透明性高、柔韧性好的纤维素气凝胶的有效的简便方法。并在此基础上，借助纤维素分子结构、聚集态结构及孔结构等多尺度结构上的协同作用，在纤维素溶液或纤维素凝胶中引入纳米填料和强相互作用对基体进行增强，特别是原位形成的无机纳米颗粒，成功获得了具有荧光、阻燃等不同功能性的，兼具良好透明性和柔韧性的高强度的纤维素复合气凝胶，实现纤维素基气凝胶的高性能化。通过本项目的工作，一方面在理论上深化对纤维素基气凝胶的制备—多尺度结构—使用性能内在关系的认识；另一方面在应用上拓展纤维素基气凝胶的性能范围，为高性能材料的开发和应用提供研究基础。