Fabrication of sandwich-structured cellulose composite membranes for switchable infrared radiation

Developing a feasible and efficient biomass-based membrane for energy-saving applications is critical for addressing greenhouse effect and energy crises. Herein, a sandwich-structured cellulose composite membrane with controllable thermal management properties was fabricated via the assembly of Ag nanoparticles/cellulose (ANPs/C), ultralong MnO 2 nanowires (UMNWs), and MnO 2 nanosheets/cellulose (MNSs/C). In this strategy, the UMNWs as building blocks were prepared by hydrothermal method. Then, the ANPs/C and MNSs/C were fabricated via magnetron sputtering and in situ growth method, respectively. Finally, the cellulose composite membrane (CCM) was fabricated via vacuum-filtration of cotton cellulose (CC), UMNWs and MNSs/C suspension, and subsequently the CC surfaces were covered with the ANPs by magnetron sputtering. The sandwich-structured CCM exhibits Janus infrared radiation properties due the asymmetrical surface structure and chemical compositions. The ANPs layer has high infrared reflectivity of 91.6%, however, the MNSs/C layer shows the low infrared reflectivity with 62.7%. The results indicate that the Janus sandwich CCM not only can efficiently reflect infrared heat back toward the body, in order to achieve highly thermal insulating under low temperature environment, but also can achieve highly passive cooling under high temperature environment. In addition, the CCM exhibits excellent antibacterial properties due to presence of ANPs, which is beneficial to enhance the lifespan of the personal thermal management membrane. The present work may give some insight to prepare sandwich-structured membranes with controllable thermal management properties for application in wearable textiles. Graphic abstract