Hydrogen bonds leading nanodiamonds performing different thermal conductance enhancement in different MWCNTs epoxy-based nanocomposites

The lack of thermal conductance (TC) remains to be a challenge for epoxy resin. Fortunately, the thermal conductance of epoxy resin can be effectively improved by filler incorporation. Recently, compositing epoxy resin with hybrid filler system has been the direction for the development of next-generation thermal conductive functional materials. In this paper, epoxy-based nanocomposites containing nanodiamonds (DNDs)/pristine multi-walled carbon nanotubes (p-MWCNTs) and DNDs/KH550 functionalized MWCNTs (MWCNTs-KH) as the hybrid filler system were prepared respectively, and the thermal conductance of the nanocomposites was compared. The addition of DNDs was found to play a dominating role in the MWCNTs-KH filler systems (0.2 g, from 0.30 W/mK to 0.34 W/mK), but hardly has any effect on the p-MWCNTs filler system (0.2 g, from 0.24 to 0.26 W/mK only). Furthermore, the TC of the DNDs/MWCNTs-KH (2 g) epoxy-based nanocomposite increased to 0.45 W/mK, displaying an enhancement of 114.2 %. A shift of 5 cm-1 recorded by FTIR and the shift of C=O revealed by XPS for DNDs/MWCNTs-KH strongly confirmed the existence of hydrogen bonds. Associating with the characterization results of SEM, TEM and dispersion qualitative experiment, the significant improvement in the TC of DNDs/MWCNTs-KH (2 g) epoxy-based nanocomposite was attributed to the hydrogen bond attachment between DNDs and MWCNTs-KH. The mechanism is that the attachment improves the dispersion of the fillers in epoxy, leading to the formation of a more effective thermal conductive network, thus, the enhanced TC. This work may inspire future studies in hybrid filler recognition and self-assemble technology via hydrogen bonds.