Ultraviolet light crosslinked graphene/multi-walled carbon nanotube hybrid films for highly robust, efficient and flexible electrothermal heaters

Based on the Joule heat effect, graphene can transfer electrical into heat energy with fast response times and high efficiencies. Despite intensive researches, facile strategies for preparing polymer-based graphene electrothermal materials remain highly desirable. We herein report a strategy for preparing poly (tetra fluoroethylene) (PTFE)-supported high-performance hybrid electrothermal films from liquid-phase exfoliated graphene by combining with multi-walled carbon nanotubes (MWCNTs). The graphene and MWCNT dispersions can be obtained by sonicating graphite and MWCNTs, respectively, in chloroform with an ultraviolet (UV) light reactive dendritic polymer, HBPE@Py@Acryl, as stabilizer. Further, a series of PTFE-supported, UV cross-linked graphene/MWCNT hybrid films were successfully prepared from the dispersions by vacuum filtration and UV irradiation. It is found that the existence of MWCNTs in the films results in porous structure, making the hybrid films denser than the single graphene system. Meanwhile, the MWCNTs can effectively bridge graphene nanosheets to form perfect hybrid networks, jointly imparting the films with significantly enhanced electrothermal performance. In addition, the UV crosslinking of the HBPE@Py@Acryl adsorbed on the graphene and MWCNT surfaces makes the films exhibit excellent service stability. As an example, after being alternately folded 1800 times or scraped for 90 cycles, the film with 20% MWCNTs remains exhibiting stable, well controllable electrothermal performance. This research provides a guideline for producing high-performance polymer-based graphene electrothermal materials, potentially useful in wearable devices and intelligent actuators, from liquid-phase exfoliated graphene through simple process.