Construction of a high breathability hydrophobic-hydrophilic Janus bilayer fiber structure through chemical treatment

Hydrophobic-hydrophilic Janus membranes show potential in functional thin membrane devices due to their programmability and high flexibility. However, the existing Janus membranes are limited by issues such as high fabrication costs, poor interfacial bonding, and limited long-term operational capabilities. In this study, a hydrophobic-hydrophilic Janus structure membrane was developed by electrospinning and chemical treatment successfully, using hydrophilic copper nanoparticles and hydrophobic thermoplastic polyurethane (TPU). The obtained membrane showed significant differences in wetting behavior on both sides, with water contact angles of 116.50 +/- 2.00 degrees and 68.00 +/- 1.00 degrees, indicating pronounced hydrophobic-hydrophilic contrast. Furthermore, the hydrophobic-hydrophilic Janus membrane exhibited tight interfacial bonding, high breathability (under a gas flow of 8.26 m3 h-1 and 11.67 m3 h-1), and an extraordinarily high water absorption capacity of 2340%. This novel approach holds promise for the development of functional thin membrane devices like unidirectional infiltration and desalination. Hydrophobic-hydrophilic Janus-structured membranes based on a homogeneous matrix were constructed by electrospinning and chemical treatment, and exhibited excellent air permeability.