驻极纳米纤维膜的可控制备及其特异化过滤机理研究

To obtain the characteristics of both high-filtration efficiency and low-pressure drop is always a big challenge for air filtration materials. Compared with ordinary fibers, electrospun fibers have smaller diameter and larger specific area, and therefore, if they are stably electreted, the filtration properties of high-filtration efficiency and low-pressure drop of the formed nanofibrous membranes are greater growth and upside potential. Herein, we will study the internal relation between the microstructure and the filtration performance of the electreted nanofibrous membranes, reveal the specific filtration mechanisms of the membranes, to improve the high-efficiency and low-pressure drop properties. Recently, the electreted effect of electrospun fibers has started to be reported, but its formation conditions, control mechanisms and particle trapping mechanism under electrostatic field are not clear. In this work, we will investigate the influences of solution characteristics, additives and process parameters on the formation of electrospun fibers with high charge density and stable electreted effect, master the formation conditions and control methods, reveal the particle trapping mechanism under electrostatic field, illuminate the internal relation between the structure and surface chemical properties of the membrane and its filtration performance, and finally optimize the structure of the nanofibrous membranes, to achieve the target of filtration efficiency over 99.995% and pressure drop below 50 Pa, and therefore to fulfill the practical applications in the air filtration fields.

高精度过滤效率的同时满足低压阻的要求是空气过滤材料一直面临的重大难题。较普通纤维，静电纺纳米纤维直径更小，比表面积更大，如能实现它的稳定驻极化，其高效低阻过滤性能具备更大的提升空间。本项目拟对静电纺驻极纳米纤维膜微观结构与其过滤性能的内在关联展开研究，揭示纤维膜特异化过滤机理，从而提升其高效低阻过滤性能。近年来，有关静电纺纳米纤维的驻极效应始有报道，但其成型条件、调控机制及电场捕获机理都尚未明确。本项目将阐明原液特性、添加物及纺丝加工参数对高密度电荷、长效稳定驻极纳米纤维成型的影响规律，明确成型条件并掌握调控方法，揭示颗粒流经驻极纳米纤维膜的电场捕获机理，明晰纳米纤维膜本体结构、表面化学性质与其过滤性能（过滤效率、空气阻力）之间的内在联系，并在此基础上对驻级纳米纤维膜的结构进行优化，实现其过滤效率达到99.995%、空气阻力低于50Pa的目标，以满足其在空气过滤领域高效低阻的应用要求。

随着工业的发展，空气污染问题也越来越严重。近年来，我国多地持续出现雾霾天气。采用高效空气过滤材料拦截微细颗粒物是实现对雾霾污染有效防护的重要措施。而高精度过滤效率的同时满足低压阻的要求是空气过滤材料一直面临的重大难题。申请者现制备出一种静电纺驻极纳米纤维膜，可有效解决这一问题。静电纺纳米纤维具有直径小，比表面积大的优势，而驻极效应是在纤维成型过程中将电荷注入纤维内部，能够实现稳定驻极化，从而提升材料的高效低阻过滤性能。本项目通过在纺丝液中添加驻极体微粒，增加纤维膜电荷储存量，制备出具有优异空气过滤性能的静电纺驻极纳米纤维膜，并对其结构性能的影响因素进行探究，揭示其过滤机理和内部联系。项目执行期间主要开展了以下几个方面的研究工作：（1）从驻极体添加物的性质出发，系统研究了驻极体添加物的微粒直径、含量对纳米纤维膜结构性能的影响；探究和验证了电荷在纤维膜的储存机制和电场捕获机理；并基于以上研究成果确定了合适的驻极体微粒粒径和含量；（2）调控工艺参数和测试条件，研究在其影响下的纤维膜结构性能变化，着重考虑了注入电压的影响；同时也考察了克重、空气流速和颗粒物种类等对纤维膜性能的影响；（3）制备了以聚偏氟乙烯（PVDF）为聚合物原料，聚四氟乙烯（PTFE）为驻极体的静电纺驻极纳米纤维膜，通过各项参数调控，实现过滤效率为99.999%、空气阻力为48.5Pa，以满足其在空气过滤领域高效低阻的应用要求。经过三年的研究，现已顺利完成任务书中规定的任务，项目执行期间在ACS Applied Materials & Interfaces、Small、Scientific Reports等杂志发表SCI论文15篇，申请专利15项，获授权4项，共培养研究生7名，其中博士2名，硕士5名，本项目的完成对探究驻极纳米纤维膜的特异性机理，实现其可控制备以及在空气过滤领域的应用具有重要意义。