Water-Based Polyurethane Heating Film with Double-Layer Conductive Network for a Rapid Electrothermal Response

Carbon-based composite materials have garnered widespread attention in the field of personal thermal management (PTM). In these applications, constructing conductive fillers with a highly cross-linked network is key to achieving the rapid electrothermal conversion of materials. Herein, a novel carbon-based composite material is successfully developed using screen printing technology, with a waterborne polyurethane (WPU) matrix embedded with carbon nanotubes (CNTs) and calcein-modified graphene nanosheets (CAG). Due to the strong π–π conjugation interactions present in the highly cross-linked carbon-based network, the resulting CAG-CNTs/WPU composite forms a 3D conductive network, which not only demonstrates a significant synergistic effect but also facilitates efficient transport of electrons and phonons. Experimental results show that the CAG-CNTs/WPU composite possesses excellent electrothermal conversion properties and an upper high thermal conductivity (3.10 W m −1 K −1 ). At a low voltage of 5 V, the composite exhibits a rapid response, increasing to 50 °C in 20 s. This research not only highlights the importance of adopting environmentally friendly preparation methods but also emphasizes the synergistic role played by 2D graphene nanosheets and 1D CNTs in building an efficient 3D electrothermal network, which has significant scientific and application value in advancing PTM applications.