Polymer/MOP-derived multilayer fibrous membranes for moisture-wicking and efficient capturing both fine and ultrafine airborne particles

Particulate matter (PM)-induced air pollution has become a serious threat to public health in many regions. There is, therefore, a need for development of advanced respirator materials that can efficiently capture PM and also exhibit both low breathing resistance and good moisture wicking properties to ensure physiological comfort of the wearers. Herein, we report a new type of multilayer membranes that exhibit excellent filtration efficiencies for PM of various sizes, low air resistance and good directional moisture transport properties. We incorporated a type of metal-organic framework, ZIF-8, into polyacrylonitrile (PAN) to prepare microfibers with high surface roughness, and altematingly stacked layers of rough microfibers with layers of PAN nanofibers via electrospinning, resulting in multi-level structured membranes. Moreover, subsequent acid and base treatments could not only tailor the hydrophilicity of fiber surfaces, but also induce multiscale surface roughness, facilitating both moisture wicking and PM adsorption. This allowed us to construct a unique multilayer membrane composed of a super-hydrophilic outer layer made of PAN fibers with multiscale surface roughness, a hydrophilic composite intermediate layer consisting of porous PAN-ZIF-8 microfibers and PAN nanofibers, and a hydrophobic polystyrene fibrous inner layer, which could offer excellent directional moisture transport performance and a high water vapor transmission rate of 10.56 kg m(-2) d(-1) due to strong capillary force and push-pull effect More importantly, benefiting from the large specific surface area, rough fiber surface, and hierarchical pore structure, the membrane exhibits high removal efficiencies of 99.973% for 0.3-um particles and 99.99% for particles of other sizes, including the more harmful ultrafine particles, at a low pressure drop of 80.1 Pa. Moreover, the multilayer composite filter still maintains a high removal efficiency of 99.951% after continuous air purification for 48 h in a high PMzs concentration ( > 300 mu g m(-3)) environment. These make such membranes promising high-performance filtration media for respirator applications.

颗粒物（PM）引起的空气污染已成为许多地区对公共健康的严重威胁。因此，需要开发先进的呼吸器材料，其可以有效地捕获PM并且还表现出低呼吸阻力和良好的吸湿排汗性能以确保佩戴者的生理舒适性。在此，我们报道了一种新型的多层膜，该膜对各种尺寸的PM表现出优异的过滤效率，低空气阻力和良好的定向水分传输性能。我们将一种金属有机骨架ZIF-8掺入聚丙烯腈（PAN）中，以制备具有高表面粗糙度的超细纤维，并通过静电纺丝将PAN纳米纤维层与粗糙的超细纤维交替堆叠，从而形成多层结构化膜。而且，随后的酸和碱处理不仅可以调整纤维表面的亲水性，而且可以引起多尺度的表面粗糙度，从而促进吸湿排汗和PM吸附。这使我们能够构建一种独特的多层膜，该膜由具有多尺度表面粗糙度的PAN纤维制成的超亲水性外层，由多孔PAN-ZIF-8超细纤维和PAN纳米纤维组成的亲水复合中间层以及疏水性聚苯乙烯纤维内层组成层，由于强大的毛细作用力和推拉效应，可提供优异的定向水分传输性能和高水蒸气透过率10.56 kg m（-2）d（-1）更重要的是，得益于较大的比表面积膜具有粗糙的纤维表面和分层的孔结构，在80.1 Pa的低压降下，膜对0.3um颗粒的去除效率高达99.973％，对于其他尺寸的颗粒（包括危害更大的超细颗粒）则达到99.99％。 ，多层复合过滤器在高PMzs浓度（> 300）下连续空气净化48小时后仍能保持99.951％的高去除率。 mu g m（-3））环境。这些使此类膜成为呼吸器应用中有望使用的高性能过滤介质。

Published: 2020

Journal ：SEPARATION AND PURIFICATION TECHNOLOGY

Impact Factor：6.195

Paper link: https://www.sciencedirect.com/science/article/abs/pii/S1383586619303156