Janus cellulose-based fabric with rapid heat conduction and intelligent water management capabilities.

Cellulose-based personal thermal management (PTM) fabrics have attracted considerable attention due to their excellent moisture absorption and breathability. However, most current PTM textiles have single functionalities and rely on constant, passive moisture transport, failing to dynamically regulate water according to the environment. Herein, a Janus cellulose-based fabric (Janus CF) with an asymmetric interfacial structure was successfully fabricated by coating hydroxylated boron nitride nanosheet (BNNS-OH) and Titanium dioxide (TiO2) sol. The prepared Janus CF exhibits a 79.17% rise in in-plane thermal conductivity compared with pristine cellulose fabric, achieving a cooling effect of 2.3 °C. Meanwhile, the fabric can switch the channel of water transport spontaneously depending on ambient ultraviolet (UV) irradiation. When Janus CF is exposed to a rainy or indoor environment, both sides of Janus CF remain hydrophobic, which prevents the intrusion of rainwater, reducing moisture permeability. Conversely, after 90 min of UV irradiation, Janus CF affords a unidirectional water transport index of 494.95% and an enhanced evaporation rate of 137.93 g·m-2·h-1, with a wettability gradient formed, significantly boosting sweat elimination and evaporation. This design allows adaptive water transport to synergistically integrate with thermal conduction, maximizing personal comfort in rainy or sunny weather.