Multi-scaled interconnected inter- and intra-fiber porous janus membranes for enhanced directional moisture transport

Growing use of comfortable functional textiles has resulted in increased demand of excellent directional moisture (sweat) transport feature in textiles. However, designing such anisotropic functional textiles that allow fast penetration of sweat through one direction but prevent its movement in the reverse direction is still a challenging task. In this regard, fabrication of a novel Janus membrane with multi-scaled interconnected inter- and intra-fiber pores for enhanced directional moisture transport designed by a rational combination of superhydrophilic hydrolyzed porous polyacrylonitrile (HPPAN) nanofibers and hydrophobic polyurethane (PU) fibers via electrospinning may be a very useful approach.

PAN/PVP composite nanofibers were electrospun using PAN/PVP composite solution dissolved in DMF. After electrospinning, electrospun fibers were subjected extensive washing process to selectively remove PVP from the fiber matrix to develop highly rough and porous PAN (PPAN) nanofibers. The resultant PPAN nanofibers were then hydrolyzed to further improve their wettability. Finally, a layer of PU fibers was directly deposited on the HPPAN nanofibers via electrospinning to fabricate the subsequent Janus membrane.

The resultant PU/HPPAN Janus membranes display instant moisture transport in the positive direction with exceptional directional moisture transport index (R = 1311.3%), whereas, offer superior resistance (i.e. breakthrough pressure ≥17.1 cm H₂O) to the moisture movement in the reverse direction. Moreover, a plausible mechanism articulating the role of inter- and intra-porosity for the enhanced directional moisture transport has been proposed. Successful fabrication of such fascinating Janus membranes based on the proposed coherent mechanism opens a new insight into the engineering of novel functional textiles for fast sweat release and personal drying applications.