Covalently interconnected carbon nanotubes network enhancing thermal conductivity of EP-based composite

The miniaturization of integrated circuits promotes the rapid rise of polymer-based carbon nanotubes (CNTs) thermal conductive composites. However, the unordered arrangement structure and interfacial thermal resistance of CNTs become important obstacles affecting their application. The directional orientation driven of CNTs by external force and the "bridge" between CNTs constructed via covalent bonding could solve these issues. Herein, the freeze-casting orientation configuration and new CNTs grew in situ by ZIF-67 constructed the hierarchical structure of CNTs in epoxy resin (EP)-based composites. The composites with directional networks of interlinked CNTs achieve an out-plane thermal conductivity value (κ⊥) of 0.98 W m−1 K−1 at filler loading of 5.8 vol%, which is 4.85 times high than that of pure EP. More importantly, non-equilibrium molecular dynamics (NEMD) simulations validated the advantage of using covalent bonding to connect CNTs. This work provides a way for the reasonable design of polymer-based CNTs thermal conductive composites.