Development of coaxial double blow solution blow spinning technique for preparation of superfine fibers and its application in air filtration

Solution blow spinning (SBS) has recently become the subject of much interest in superfine fiber production, with filtration, insulation, and healthcare applications. However, research on enhancing production efficiency and designing industrial equipment remains scarce. Efforts to increase nozzle numbers for mass production have introduced complexities in control and maintenance, posing challenges to industrial adoption. Thus, a coaxial double blow (CDB)-SBS technique was developed to enhance the production efficiency of SBS and facilitate its industrialization, incorporating a three-channel coaxial nozzle design (airflow–solution–airflow), utilizing double high-speed airflows to elongate the spinning solution, in contrast with conventional SBS nozzles. Numerical simulations were used to investigate the distribution law of the double-layer airflows at the nozzle outlet, revealing turbulent conditions within 0.5 mm of the needle, after which airflow velocity increased rapidly in the same direction. Stability between the two airflows is achieved only when their velocities align; this is facilitated by their symmetrical distribution. Experiments using a polystyrene/ N , N -dimethylformamide solution demonstrated optimal fiber morphology—free of droplets or curled fibers—at airflow velocities of 100 m/s for both layers. Further experiments with such polymers as polyacrylonitrile, polyurethane, polyvinyl acetate, polyvinylidene fluoride, and polyvinylpyrrolidone confirmed the capability of this nozzle to produce superfine fibers, increasing yield by over 50% compared with traditional SBS under optimal conditions. Additionally, a composite window screen, fabricated using the CDB-SBS technique, exhibited superior air filtration performance against particulate pollution. The practicability and significant potential of the CDB-SBS technology and nozzle design offer crucial insights for developing industrialized SBS equipment.