Trilayered Textile Systems with Asymmetric Wettability and Pore Structure for Directional Water Transport. Part I: Fabrication and Characterization of Bilayered Nanofibrous Membrane Systems

Asymmetric wettability and pore structure are important factors that affect moisture transport in multilayered porous materials. In this study, bilayered composite nanofibrous membrane systems with asymmetric wettability and pore structure were fabricated by electrospinning polyurethane (PU)/poly(ethylene glycol) diacrylate (PEGDA) blend solutions, followed by PEGDA coating to develop functional textiles with enhanced directional moisture transport. The hydrophilicity of the membranes was tailored by varying the ratios of PU and PEGDA blend solutions, and a weakly hydrophobic nanofibrous membrane was fabricated. The composite membranes were then pour-coated with PEGDA and photocrosslinked at various degrees by varying the UV irradiation time to control the degree of PEGDA coating and pore size of the bilayered membrane systems. The results confirmed that a hydrophilic PEGDA coating layer was formed on the weakly hydrophobic PU/PEGDA nanofibrous membrane surface, and the pore size of the bilayered membrane systems was controlled by adjusting the degree of PEGDA coating via the UV irradiation duration. The bilayered membrane systems with asymmetric wettability and pore structure improved water transport properties, inducing a push–pull effect to transfer water from the weakly hydrophobic PU/PEGDA membrane to the hydrophilic PEGDA coating layer. Asymmetric bilayered membrane systems will be combined with conventional tricot fabrics to construct trilayered textile systems with pore size and wettability gradients in the second part of the study, and the moisture transport properties of the trilayered textile structure will be investigated for the development of textiles with advanced moisture management.