Self-Powered, Biodegradable, and Antibacterial Air Filters Based on Piezoelectric Poly(L-Lactic Acid) Nanofibrous Membranes

Particulate matter (PM) and infectious bacteria spreading by the air are extremely harmful to human health. The performance of masks significantly deteriorates in humid air because the surface charges are attenuated or neutralized. Moreover, most masks are made of nondegradable materials such as polypropylene nonwovens. In this study, we report a self-charged, biodegradable, and antibacterial poly-(L-lactic acid) (PLLA) nanofibrous mask by electrospinning, which combines mechanical sieving and electrostatic adsorption to capture PM and bacteria. The controllable and stable piezoelectricity of the PLLA membranes generates surface charges to boost the filtration performance. The PLLA masks exhibit not only high filtration efficiency (98.38% for NaCl particles and 92.40% for oil particles) but also good air permeability (156 Pa for NaCl particles and 162 Pa for oil particles). Due to the piezoelectricity of the oriented PLLA membrane, it maintains excellent filtration performance in humid air or after long-term storage. In addition, the incorporation of hexadecyltrimethylammonium bromide (CTAB) endows the fibrous membrane with antibacterial properties. Results also confirmed that the PLLA mask is degradable. This work provides a convenient strategy to fabricate piezoelectric, biodegradable, and antibacterial poly-(L-lactic acid) nanofibrous membranes, which show great potential in various fields, such as air filtration.