基于聚合物/溶胶相分离的柔性氧化硅纳米纤维膜成型机理及增强机制研究

Silica nanofibrous materials with high-temperature resistance, high porosity, and small pore size could act as a light and high-efficiency thermal insulation materials for applications in fields such as aerospace, building, and transportation. However, most silica nanofibrous materials are fragile, which have restricted their practical applications. Recently, we have fabricated the silica nanofibrous materials with certain flexibility, but the mechanical properties were difficult to meet the requirement in actual applications. This proposal is aiming to solve the important issues including the mechanism for the phase separation of polymer/sol and the flexibility of silica nanofibrous materials. The proposal will mainly focus on the researching the effect of the separation of polymer/sol on the mechanical properties of silica nanofibrous materials, which will carried out from analyze the physicochemical properties of polymer/sol to reveal the mechanism of polymer/sol separation in electrospinning process. In order to demonstrate the optimized structure of silica nanofiber when it obtains the optimal flexibility, we need to clarify the effect of polymer/sol separation on the formation and microstructure of silica nanofibers, build up the association between the microstructure and mechanical properties of silica nanofibrous materials. Finally, the goal for fabricating the silica nanofibrous materials with tensile stress of 10 MPa and tensile strain of 15% will be achieved to satisfy the requirements in the filed of high temperature thermal insulation.

氧化硅纳米纤维材料具有耐高温、孔隙率高、孔径小等优点，是一种轻质、高效的耐高温隔热材料，但是现有氧化硅纳米纤维材料普遍存在脆性大、不耐振动、结构易被破坏等缺陷，难以满足高温隔热材料领域的实际应用需求。通过采用静电纺丝方法，申请者获得了柔性氧化硅纳米纤维，但是该材料的力学性能仍不能满足实际应用。针对氧化硅纳米纤维制备过程中聚合物/溶胶体系相分离机制不清晰、柔性机理尚不明晰等关键科学问题，本项目将开展聚合物/溶胶体系相分离过程对力学性能影响机制研究，考察聚合物/溶胶体系相分离过程中体系物理化学性质的变化规律，揭示静电纺丝过程中溶剂诱导聚合物/溶胶体系快速相分离的机制，阐明聚合物/溶胶相分离过程对纤维成型及微观结构的影响规律，明晰微观结构与力学性能间的参数关联，建立增强氧化硅纳米纤维膜力学性能的科学方法，实现纤维膜拉伸强度>10MPa、断裂伸长率>15%的目标，以满足高温隔热领域的应用需求。

陶瓷纳米纤维材料因具有孔隙率高、孔径小、三维连通曲泽孔结构，在油水分离、隔热、催化等领域具有广泛的应用前景，但现有的陶瓷纳米纤维普遍存在脆性大、易断裂，而目前制备的柔性陶瓷纳米纤维材料仍存在的力学性能不足、柔性机理不明晰、种类少等瓶颈问题。针对该问题，本项目研究了均一、稳定聚合物/溶胶体系成型的边界条件，分析了静电纺丝过程中溶剂诱导聚合物/溶胶体系相分离的过程及机制，探究了聚合物/溶胶相分离过程对纤维成型及微观结构的影响规律，揭示了陶瓷纳米纤维微观结构与力学性能间的构效关系，制备出了具有良好柔韧性的SiO2串珠/纤维复合膜材料和力学增强型SiO2纳米纤维基复合材料，其拉伸强度为5.8MPa、断裂伸长率为13%、弹性模量为1.6MPa，同时还扩展制备出了结晶型柔性锆掺杂钛酸锶、钛酸钡纳米纤维膜材料，探索了柔性陶瓷纳米纤维材料在高效油水分离、可见光催化、抗菌等领域的应用。