MXene based flexible Janus nanofibrous membrane composite for unidirectional water transportation

Smart textiles/fabrics with unidirectional water transportation (UWT) capability have wide applications in wearable electronics. The unidirectional water transportation capability can effectively help the fabrics expel the sweat from people's skin while prevent the aqueous solution penetrating the fabrics. It is still challenging to develop stretchable and multifunctional fabrics with durable UWT performance. Herein, we report a flexible MXene based Janus nanofibrous membrane (JNM) by integration of one thick superhydrophilic MXene/chitosan decorated polyurethane (PU) nanofiber (MCP) layer and the other thin hydrophobic MXene coated PU nanofiber (MP) layer. Benefiting from the PU nanofiber core/MXene shell structure, abundant pores are preserved inside the MCP layer. The chitosan can greatly improve the hydrophilicity of the MCP layer and also the interfacial interaction between the MCP and MP layer. The UWT time for the JNM is 18 s, and the UWT behavior can be maintained during various durability tests. In addition, the JNM exhibits a unique anti-gravity UWT capability. The JNM with excellent photothermal conversion performance are used as wearable temperature sensors that can provide temperature alarms during extremely hot and cold weather. The flexible and multifunctional JNM shows broad application prospects in smart and wearable electronics.