Polyacrylonitrile Nanoyarn Fabrics with Tailored Asymmetric Wettability for Efficient Unidirectional Moisture Transport.

Unidirectional moisture-wicking fabrics are crucial for thermal comfort in hot and humid environments. However, existing commercial fabrics often suffer from a low sweat transfer rate, leading to discomfort and low working efficiency. Herein, we propose a strategy to fabricate unidirectional moisture-wicking fabrics with tailored asymmetric wettability based on polyacrylonitrile (PAN) nanoyarn. Hydrophilic PAN nanoyarns were fabricated via dual-nozzle electrospinning at an optimized funnel rotational speed to ensure structural uniformity. Hydrophobic (PAN@FPU) nanoyarns were obtained by dip-coating with a low-surface-energy fluorinated polyurethane (FPU). Subsequently, the PAN nanoyarns and PAN@FPU nanoyarns were woven together to obtain the hydrophobic layer, and the PAN nanoyarns were woven into the hydrophilic layer with a plain weave structure. The hydrophilic layer possessed microscale hydrophilic channels between PAN nanoyarns and nanoscale hydrophilic channels between PAN nanofibers, and the multiscale composite porous structure resulted in rapid liquid transport. The combination of the hydrophilic layer and the hydrophobic layer exhibited asymmetric wettability, resulting in good unidirectional moisture-wicking performance. The final fabrics exhibited a good accumulative unidirectional transport capacity of 418.5% and a high overall moisture management capacity of 0.79. Benefiting from stable twisted nanofibers in the nanoyarn and the interlacement structure of warp/weft yarns, the obtained nanoyarn fabrics demonstrated good mechanical properties, showing considerable potential for application in moisture transport fabrics for thermal-wet management of the human body.