A cellulose-based membrane with temperature regulation and water transportation for thermal management applications

Thermal management materials are widely employed in the construction and textile industries due to their non energy input and the ability to precisely adjust the temperature. However, the application of thermal management technique toward sustainable agriculture is still challenging due to the complex environment. Herein, a coupled insulation system with highly asymmetric thermal conductivity and unidirectional water penetration is developed by using the integration of thermal management and water diodes technologies. The hierarchical membrane shows asymmetric thermal conductivity of carbonized cellulose layer (CCL, 0.64 W m-1 K-1) and Al2O3/cellulose layer (ACL, 0.16 W m-1 K-1), and good moisture permeability owing to the anisotropic wettability of the material and hierarchical structure design. Thermal management performance revealed that compared with PET and cellulose membrane, the membrane temperature increased by 4.1 & DEG;C and 1.3 & DEG;C, respectively, resulting in a decrease in greenhouse heat dissipation. Besides, benefitting from the efficient photothermal conversion performance of carbonized cellulose, the outside can rapidly warm up to 42 & DEG;C under 120 W/m2 sun radiation, providing a suitable growth temperature for crops. Meanwhile, unidirectional water penetration achieved in the 60 s not only enables the membrane to maintain long-term and effective insulation, but also ensures the demand of crops for water during drought conditions. Furthermore, the anti-flaming property broadens the range of applications, reducing damage in an emergency such as a fire. The demonstrated membrane can potentially replace the commercial plastic-based greenhouse materials, and the gradient and bilayer design open a new avenue for sustainable thermal management application.