Multifunctional Janus fibrous hybrid membranes with sandwich structure for on-demand personal thermal management

Developing functional Janus membrane with asymmetric infrared emissivity for personal thermal management is of significance but challenging, due to the difficulty in controlling the infrared insulation and infrared dissipation to satisfy the personal thermal comfort. Herein, a multifunctional Janus Cu/MnO2/cellulose@Layered Double hydroxide fiber (CMCFL) membrane with sandwich structure has been fabricated by vacuum filtrating ultralong MnO2 nanowires and Cu nanowires sequentially on cellulose fiber@Layered Double Hydroxide (LDH) basement membrane. The obtained CMCFL membrane allows for an integration of low infrared emission, promising electrical conductivity, antibacterial property from Cu nanowire layer, and high infrared emission from cellulose@LDH layer. Moreover, the Janus CMCFL membrane shows the asymmetrical characteristics of infrared radiation for on-demand personal thermal management: the low-emissivity layer (Cu nanowires layer) is facing outside to reduce the human thermo radiation, and high-emissivity layer (cellulose@LDH layer) is facing outward to enhance the human thermo radiation. In addition, the promising electrical conductivity of Cu nanowires layer endows the superior Joule heating for extra warmth of 19 degrees C using a low supply voltage around 8.4 V to enhance the thermal comfort in the cold environment. Besides, the obtained Janus CMCFL membrane not only shows good breathability and flexibility, but also possesses other desired properties including excellent interfacial compatibility and antibacterial activity for wearability. The outstanding integrated properties and corresponding design strategy of Janus CMCFL membrane are expected to be applicable in the fields of personal thermal management, providing a promising direction for the development of wearable textile to enhance the adaptability of human skin to the environment.