Biodegradable MOFilters for Effective Air Filtration and Sterilization by Coupling MOF Functionalization and Mechanical Polarization of Fibrous Poly(lactic acid)
Xinyu Li, Guiying Zhu, Mengke Tang, Tian Li, Cunmin Wang, Xinyi Song, Shenghui Zhang, Jintuo Zhu, Xinjian He, Minna Hakkarainen, Huan Xu
Abstract
High-performance air filtration materials are important for addressing the airborne pollutants. Herein, we propose an unprecedented access to biodegradable poly(lactic acid) (PLA)-based MOFilters with excellent filtering performance and antibacterial activity. The fabrication involved a stepwise in situ growth of zeolitic imidazolate framework-8 (ZIF-8) crystals at the surface of microfibrous PLA membranes, followed by mechanical polarization under high pressure and low temperature (5 MPa, 40 °C) to trigger the ordered alignment of dipoles in PLA chains and ZIF-8. The unique structural features allowed these PLA-based MOFilters to achieve an exceptional combination of excellent tensile properties, high dielectric constant (up to 2.4 F/m), and enhanced surface potential as high as 4 kV. Arising from the remarkable surface activity and electrostatic adsorption effect, a significant increase (from over 12% to nearly 20%) in PM 0.3 filtration efficiency was observed for the PLA-based MOFilters compared to that of pure PLA counterparts, with weak relation to the airflow velocities (10–85 L/min). Moreover, the air resistance was controlled at a considerably low level for all the MOFilters, that is, below 183 Pa even at 85 L/min. It is worth noting that distinct antibacterial properties were achieved for the MOFilters, as illustrated by the inhibitive rates of 87 and 100% against Escherichia coli and Staphylococcus aureus, respectively. The proposed concept of PLA-based MOFilters offers unprecedented multifunction integration, which may fuel the development of biodegradable versatile filters with high capturing and antibacterial performances yet desirable manufacturing feasibility.