梯度浸润纳米纤维滤材的可控构建及其过滤机理研究

The development of nanofiber based filtration membrane with good moisture permeability, high filtration efficiency, and low pressure drop has an important significance to improve the comprehensive performance of PM2.5 respirators. Herein, this proposal studies the electrospun nanofibrous membranes with gradient wettability for air filtration. We will study the influence of solution characteristic and process parameters on the microstructure of fibrous membranes, revealing the regulating rules of the construction of gradient wettability structured nanofibrous membranes. Through optimizing the surface modification and bulk structure of nanofibers, the synergistic coupling mechanism of the enhanced moisture vapor transmission performance will be clarified. Moreover, on the basis of the studies of microstructure, surface physicochemical properties, and filtration performance, the structure-activity relationship will be discussed. Finally, CFD technology is used to simulate PM2.5 fine particles transport process in the multistage network porous channels, thus revealing the pressure loss and fine particle filtration mechanism of the nanofibrous membranes, achieving the target of controllable fabrication of nanofibrous present high filtration efficiency over 99.99%, low pressure drop less than 80Pa, water vapor transmission over 14100g/m2/d, to fulfill the practical application in the field individual protection.

开发具有良好透湿导湿性的高效低阻纳米纤维过滤膜对提高PM2.5防护口罩的综合性能具有重要意义。本项目拟通过静电纺丝技术制备具有梯度浸润结构的纳米纤维过滤材料，考察原液特性与加工参数对材料微观结构的影响，确立纳米纤维滤材梯度浸润结构的成型边界条件；优化纤维表面化学性质和纤维本体结构，阐明二者协同改善透湿导湿性能的作用机制；进一步研究纳米纤维本体结构和表/界面理化特性与过滤性能间的构效关系；借助CFD技术仿真模拟PM2.5细颗粒物在三维多级网络孔道中的输运过程，揭示梯度浸润纤维膜的压力损失机制和特异化过滤传质机理，实现梯度浸润纳米纤维滤材对细颗粒的过滤效率>99.99%、阻力压降＜80Pa、透湿通量>14100g/m2/d的目标，以满足其在个体防护领域的应用需求。

纤维材料是防护口罩的主要核心过滤介质，而传统驻极熔喷纤维无纺布核心滤材普遍存在纤维膜克重大、高湿环境电荷衰减速率大和性能不稳定等缺陷，极大的限制了其在个体防护领域的应用。为此，本项目围绕对纳米纤维结构进行可控设计并对其进行表/界面功能化修饰，并对其在PM2.5空气过滤领域的应用等方面开展了一系列研究。项目执行期间主要开展了以下几个方面的研究工作：（1）PES溶液中引入无机驻极体BaTiO3纳米粒子获得具有粗糙结构的PES/BaTiO3复合纤维膜。在此基础上研究了透气性、过滤性能和热辐射性与纤维膜结构之间的内在关联，探索了其在高温高湿条件下作为口罩滤材的佩戴舒适性。（2）在梯度浸润膜结构设计方面，设计了一种具有超润湿结构的SiO2@PEI-PAN/SPES复合过滤膜，并对其结构和性能之间的关系进行了研究，这种通过逐层自组装方式获得的膜粗糙度可广泛适用于选择性分离领域。（3）采用静电纺丝和静电喷雾相结合的方法，制备了具有梯度浸润性的SiO2@PAN/PEI@F-SiO2复合纳米纤维膜。研究了微纳结构和梯度润湿性对单向导湿性能和过滤性能的影响，探究了浸润结构与细颗粒物在纤维膜内部过滤的关系，为高温高湿下空气过滤膜的结构设计提供指导。