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

Understanding the influence of interface on interfacial thermal resistance (R-b) 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 R-b 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 R-b, and the thermal insulating effect, negative role in reducing R-b, 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 R-b to 8.61 x 10(-9) m(2) K/W from 1.11 x 10(-8) m(2) 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 R-b affected by interfacial modification would act as guiding function in preparing high thermal conductive nacre-like layered structural films.