Hierarchical Porous Poly(L-lactic acid) Nanofibrous Membrane for Ultrafine Particulate Aerosol Filtration

Ultrafine particulate aerosols less than 100 nm diffuse randomly in the air and are hazardous to the environment and human health. However, no technical standards or commercial products are available for filtering particle sizes under 100 nm yet. Here, we report the development of a porous poly(L-lactic acid) (PLLA) nanofibrous membrane filter with an ultra-high specific surface area via electrospinning and a post-treatment process. After PLLA fibres were electrospun and collected, they were treated by acetone to generate a blossoming porous structure throughout each individual fibre. Characterizations of morphology, crystallinity, and mechanical and thermal properties demonstrated that the porous structure can be attributed to the nonsolvent-induced spinodal phase separation during electrospinning and solvent-induced recrystallization during post treatment. The blossoming porous structure with high specific surface area contributed to excellent filtration efficiency (99.99%) for sodium chloride (NaCl) ultrafine aerosol particles (30-100 nm) with a low pressure drop (110-230 Pa). Notably, under 7.8 cm/s air flow rate, the membrane samples performed better for filtering smaller-sized aerosol particles than the larger ones when evaluated by the quality factor (0.07). Finally, this finding demonstrates that the electrospun membrane with a hierarchical pore structure and high specific surface area hold great potential in applications as air-filtering materials.

小于100 nm的超细颗粒气溶胶在空气中随机扩散，对环境和人体健康有害。但是，尚无用于过滤100 nm以下粒径的技术标准或商业产品。在这里，我们通过静电纺丝和后处理工艺报告了具有超高比表面积的多孔聚（L-乳酸）（PLLA）纳米纤维膜过滤器的开发。电纺并收集PLLA纤维后，将其用丙酮处理，以在每根纤维中生成朵朵状的多孔结构。形态，结晶度以及机械和热学性质的表征表明，多孔结构可归因于电纺丝过程中非溶剂诱导的旋节线相分离和后处理过程中溶剂诱导的重结晶。具有高比表面积的朵朵多孔结构为具有低压降（110-230 Pa）的氯化钠（NaCl）超细气溶胶颗粒（30-100 nm）带来了出色的过滤效率（99.99％）。值得注意的是，在7.8 cm / s的空气流速下，用质量因子（0.07）评估时，膜样品在过滤较小尺寸的气溶胶颗粒方面要比较大的颗粒更好。最后，该发现证明具有分级孔结构和高比表面积的电纺膜在作为空气过滤材料的应用中具有巨大的潜力。

Published: 2019

Journal ：ACS APPLIED MATERIALS & INTERFACES

Impact Factor：9.002

Paper link: https://pubs.acs.org/doi/abs/10.1021/acsami.9b18083