Reliable Preparation of Biobased and Biodegradable Fibrous Membrane for Ultraefficient Air Filtration

Our previous work reported an electrospun poly(l-lactic acid) (PLLA) fiber membrane with multistructured networks (MSN) structure. It is formed by welding ribbon-like fibers and ultrafine fibers together and has been proven to be a beneficial structure for air filtration. However, there is still the problem of how to achieve the reliable preparation of this structure. In this work, the conditions and parameters for the reliable preparation of PLLA fiber membranes with an MSN structure by electrospinning technology were clarified at first. Furthermore, a complete and reasonable evolution process for the formation of this structure was proposed. Based on this, the preparation parameters of PLLA MSN membranes with excellent air filtration performance were further optimized and determined. The prepared samples successfully resolved the contradiction between filtration efficiency (99.8% for PM0.3) and pressure drop (∼20 Pa). Especially due to the piezoelectric performance of ultrafine fibers, the membrane has demonstrated a powerful interception effect on ultrafine particles, with a filtration efficiency of 99% for PM0.1 and even smaller-sized PMs. It also demonstrated excellent moisture resistance, long-term stability, and dust-holding capacity. These findings lay the foundation for the practical application of sustainable material PLLA in the field of air filtration.