Thermally conductive poly(lactic acid)/boron nitride composites via regenerated cellulose assisted Pickering emulsion approach

• PLA/BN Pickering emulsions were fabricated via RC-assisted assembly of BN. • The noncovalent interactions between BN and RC were investigated. • PLA/BN composites were prepared using Pickering emulsion templating method. • The composites exhibited a thermal conductivity of 1.06 W/m K at 28.4 wt% BN. Polymer-based thermally conductive composites have attracted tremendous interest in thermal management of electronics. However, it remains challenging to achieve high thermal conductivity partly because the difficulty to obtain favorable distribution and orientation of conductive fillers within the polymer matrix. Herein, networked boron nitride (BN) conductive pathway was realized within the poly (lactic acid) (PLA) matrix, via regenerated cellulose (RC)-assisted assembly of BN on Pickering emulsion interface based on the noncovalent interaction, followed by solvent evaporation and hot-compressing. The strong noncovalent interactions between BN and RC were found critical to enhance the wettability and stability of BN in aqueous media with a lowest mass ratio of 1:40 of RC and BN. The obtained PLA/BN composites feature a thermal conductivity of 1.06 W/(m K) at 28.4 wt% BN loading, representing an enhancement of 430% comparing to neat PLA, and the crystallinity of the composites could increase significantly from 11.7% (neat PLA) to 43.7%. This simple, environmentally friendly and effective strategy could be easily extended for effective construction of thermally conductive composites.