Thermal conductivity and closed-loop recycling of bulk biphenyl epoxy composites with directional controllable thermal pathways

Abstract

The increasing demand of thermal management materials consumes a large amount of petrochemical and inorganic mineral resources. It is essential to develop a kind of highly thermally conductive composite with realizable closed-loop recycling. Based on the covalent adaptable networks (CANs), which are filled with boron nitride (BN) and liquid metal (LM), recyclable biphenyl epoxy composites (LEP/BN/LM) with directional controllable thermal conductivity have been prepared in this study. The induced dual-aligned liquid metal and boron nitride in the preparative film composites is obtained using repeated pressing-rolling technique. The bulk composites are fabricated by film-stacking method, relying on self-healing via interesterification between each layer. By altering the stacking mode, high thermal conductivity can be obtained in the desired direction, which realizes the directional controllable high thermal conductivity. The result shows that a high thermal conductivity of 5.41 W m⁻¹ K⁻¹ can be achieved in the predominant direction of the LEP composite. The experiment indicates that the prepared composites have excellent thermal management ability. It also confirms that the filler and the organic compounds can be completely separated by mild chemical routes, which can be reused further.