Multifunctional Polymer-Encapsulated Aerogel Fibers with Thermal Insulation, Active Heating, and Phase Change Energy Storage Abilities

Developing aerogel fibers with good mechanical properties, excellent thermal insulation, and active heating abilities has great significance in realizing efficient personal thermal management. Herein, we report the fabrication of a multifunctional cellulose nanofibers/multiwalled carbon nanotubes aerogel fiber encapsulated with a thin sheath of polyacrylonitrile (PAN), through coaxial wet spinning with stepwise coagulation. The aerogel fiber exhibits good mechanical properties with a fracture strength of 2.62 MPa due to the encapsulation by PAN sheath. The structure of the aerogel fiber is featured by a porous aerogel core wrapped by a porous sheath, making the aerogel fiber have a relatively low thermal conductivity of 0.049 W/(m·K). Moreover, the aerogel fiber has both electro- and photothermal heating abilities, which benefit to realize efficient personal thermal management, as well as the thermoelectric effect to convert thermal energy into electrical energy with a Seebeck coefficient of 16.85 μV/K. Besides, the loading of polyethylene glycol transforms the aerogel fiber into phase change composite fiber with a high phase change enthalpy of 128.6 J/g. This polymer-encapsulated fiber is unique in its multifunctional integration of good mechanical property, thermal insulation, active heating, and phase change regulation abilities, offering a promising candidate for various applications in personal thermal management.