Understanding the effect of interfacial engineering on interfacial thermal resistance in nacre-like cellulose nanofiber/graphene film

Abstract Understanding the influence of interface on interfacial thermal resistance (Rb) is important in preparing polymer-based thermal conductive composites. In this work, we demonstrated the competitive relation of the interfacial hydrogen bonding interaction and the thermal insulating effect produced by polydopamine (PDA) modification on Rb in nacre-like cellulose nanofiber/graphene nanosheet (CNF/GNS) film. By increasing PDA grafting amount on GNS, both the interfacial hydrogen bonding interaction, positive role in reducing Rb, and the thermal insulating effect, negative role in reducing Rb, were reinforced simultaneously. For the CNF/GNS film with low filler loading (10 wt%), appropriate PDA grafting amount can maximize its hydrogen bonding effect and simultaneously minimize its thermal insulation effect, thus reducing Rb to 8.61 × 10−9 m2 K/W from 1.11 × 10−8 m2 K/W and improving thermal conductivity to 13.47 W/mK from 10.91 W/mK comparing to unmodified film. However, for the films with high GNS loading (50 wt%), PDA modification failed to improve the thermal conductivity since the dominant face-to-face direct contact between overlapping GNS (contact thermal resistance) was separated by PDA layer. The new understanding on Rb affected by interfacial modification would act as guiding function in preparing high thermal conductive nacre-like layered structural films.