ABSTRACT Multiscale nanofibrous membranes hold significant potential for air filtration due to their combined high efficiency and low airflow resistance. However, fabricating these membranes typically requires complex multi‐nozzle electrospinning setups. Herein, thermoplastic polyurethane (TPU) multiscale nanofibrous membranes were fabricated via a single‐nozzle, one‐step electrospinning process by regulating solvent solubility and evaporation rates. The effects of the mixed solvent system, TPU concentration, and tetrabutylammonium chloride (TBAC) content on fiber morphology, pore size distribution, and filtration performance were investigated. A multiscale structure comprising coexisting coarse and fine fibers was achieved using a DMF:THF ratio of 5:1 and a TPU concentration of 16 wt%. At a membrane thickness of 2.4 μm, the filter exhibited 97% efficiency for 300 nm particles, a pressure drop of 42 Pa, a quality factor of 0.0834 Pa −1 , and a dust‐holding capacity of 42.2 g/m 2 . These integrated properties were significantly superior to those of single‐scale fibrous membranes. This study confirms that gradient pore size design in multiscale structures effectively balances high interception efficiency with low airflow resistance, offering a feasible pathway for developing advanced air filtration materials.
Sang et al. (Tue,) studied this question.