Preparation And Properties Of Multifunctonal Cellulose Hybrid Materials For Human Thermal Management

With the continuous progress of modern society and the rapid development of emerging technology,novel materials and novel energy has developed desperately in their own fields respectively.Compared with traditional heat transfer methods,infrared radiation heat transfer has attracted widespread attention as it can promise a faster heat transfer process and directly function on the exterior surface of membrane materials in no need of any heat transfer medium.Human thermal comfort can be achieved by regulating the infrared emissivity,infrared transmittance or infrared reflectivity of wearable material via absorption or dissipation of body heat in the form of infrared radiation.Therefore,it is of great significance to develop infrared radiation materials for human thermal management,which can be energy-saving,environment-friendly and low-carbon.As one category of representative multifunctional composite materials for substrate use,the cellulose membrane material with its advantages of high efficiency,green effect,air permeability,renewability and low-cost,takes outstanding advantages in plentiful fields,such as resource utilization,intelligent weaving,energy conservation,environmental protection and low-carbon efficiency,which has gradually become a significant case for the strategy of sustainable development.Nevertheless,cellulose membranes still suffer from several critical drawbacks when in application,such as single function,surface contamination,serious loss,and short service life,which strikingly limits their application in the field of infrared radiation.The biomass cellulose has displayed excellent chemical stability and physical plasticity.Only by modifying the infrared radiation property of biomass material surface can the effective regulation of infrared radiation containing heat preservation or infrared radiation heat dissipation be fully realized.Aiming at the requirements of antibacterial activity,breathable mechanism,heat preservation and self-cleaning property of materials for human thermal management,this work has carried out a series of scientific research on the preparation and radiation properties of multifunctional cellulose hybrid membranes for human thermal management.The main research contents are as follows:1.Ag-coated cellulose/silver（CMs@Ag）composite membranes can be prepared through depositing Ag nanoparticles on the surface of reed leaf biomass cellulose（CMs）by magnetron sputtering technique.After that,stearic acid and silver nanowire pairs prepared by hydrothermal method can be used for functional surface modification of CMs@Ag membranes when the hydrophobic composite biomass cellulose hybrid membrane material（Ag-NWs/CMs@Ag）has been prepared.The morphology,structure and composition of the hybrid membranes and intermediate product can be characterized by using SEM,XRD,FT-IR and XPS techniques.The infrared radiation property（emissivity and reflectivity）,air permeability,antibacterial and self-cleaning properties of laminated membranes were studied.The obtained results reveal that due to the existence of coated-Ag and Ag nanowires,Ag-NWS/CMs@Ag has appeared extremely low infrared emissivity（0.359）,high infrared reflectivity（0.645）,extraordingary air permeability（3.0 mg/cm² h）,excellent antibacterial and self-cleaning properties,which lays a theoretical foundation for the development of infrared energy saving and practical application of wearable materials.2.Ag-coated cellulose acetate/silver（CAs@Ag）composite membranes can be prepared through depositing Ag nanoparticles on the surface of CAs@Ag cellulose acetate（CA）by magnetron sputtering technique.Then,after the Mxene films being deposited on the substrate of by vacuum suction filtration,the multifunctional cellulose hybrid membrane material（MXene/CAs@Ag）was obtained.The morphology,structure and composition of MXene/CAs@Ag membrane were characterized by SEM,TEM,XRD and EDX techniques.The infrared radiation,electromagnetic interference shielding,and mechanical properties of the MXene/CAs@Ag membrane were studied.The results showed that MXene/CAs@Ag has displayed extremely low infrared emissivity,high electromagnetic shielding performance,and mechanical strength.The electromagnetic shielding efficiency（99%）of MXene/CAs@Ag was higher than that of CMs（5%）in the range of 8.2-12.4GHz.The EMI SE/t value of MXene/CAs@Ag is 52 d B,much higher than those of CMs（15 d B）and CMs@Ag（35 d B）,which has provided a solid theoretical basis for the development of materials with both electromagnetic shielding and infrared radiation thermal preservation properties.3.Aramid nanofiber（ANFs）hydrogel with dual thermal preservation and electromagnetic shielding properties can be deposited on the MXene side of MXene/CAs@Ag.Afterwards,the ANFs hydrogel can be converted into aerogel by freeze drying,and the hybrid aerogel composites（ANFs/MXene/CAs@Ag）was obtained in the end.The microstructure,conductivity,mechanical strength,electromagnetic shielding property,and human thermal management performance of ANFs/MXene/CAs@Ag composites has been investigated in detail.The 3D conductive network could ensure ANFs/MXene/CAs@Ag exhibits high conductivity and excellent mechanical strength during repeated bending and circulative stretching.The outstanding electromagnetic interference shielding performance of ANFs/MXene/CAs@Ag composites should be attributed to the high-performance ANF layer.In addition,ANFs/MXene/CAs@Ag composites are equipped with low infrared emissivity and high infrared reflectivity.The thermal conductivity of ANFs/MXene/CAs@Ag is 60 m W m^-1 K^-1,which can be in an order of magnitude with the thermal conductivity of air(26 m W m^-1 K^-1),illustrating ANFs/MXene/CAs@Ag possesses excellent thermal preservation performance.The thermal imaging temperature of ANFs/MXene/CAs@Ag was very low（35.4℃）,which was not only lower than that of CAs（46.1℃）,but also lower than that of MXene/CAs@Ag（37.9℃）,indicating that ANFs/MXene/CAs@Ag has displayed excellent thermal preservation performance.This work has laid a solid theoretical foundation for the further development of high-performance materials in the fields of aerospace,human thermal management,and intelligent wearable electronic devices.