Promoting h-BN dispersion in cellulose-based composite by lignosulfonate for regulatable effectual thermal management

[Display omitted] •Lignosulfonate (LS) was an excellent dispersant for hexagonal boron nitride (h-BN) since its phenolic hydroxyl groups and three-dimensional structure.•Three-dimensional thermally conductive pathways were well built and optimized when the h-BN/cellulose nanofiber (CNF) ratio was 3:1 (w/w).•The through-plane thermal conductivity of LS-BN/CNF/polyvinyl alcohol (PVA) composite was high up to 1.22 W/mK.•This LS-BN/CNF/PVA composite held great practical potentials in thermal interface materials as a key building block. Hexagonal boron nitride (h-BN) is an excellent thermally conductive and electrically insulative material. However, the formation of heat transfer pathways of h-BN in thermal interface materials is restricted due to its poor aqueous dispersity. Herein, water-soluble lignosulfonate (LS) is used to promote the dispersion of h-BN, the phenolic hydroxyl and three-dimensional structure of LS could form hydrogen bonding or steric hindrance with h-BN under ultrasound treatment. After mixing with cellulose nanofiber (CNF), the three-dimensional thermally conductive pathways are built in LS-BN/CNF aerogel through freeze-drying. The results show that the through-plane thermal conductivity of LS-BN/CNF/PVA composite with 0.2 wt% LS (LS0.2-BN/CNF/PVA) exceeds 1.22 W/mK when the h-BN/CNF ratio is 3:1 (w/w), which is 6.1-fold of that of PVA film (0.20 W/mK). The initial decomposition temperature and tensile strength of LS0.2-BN/CNF/PVA composite are 205 °C and 38.5 MPa, respectively, demonstrating acceptable thermal stability and mechanical properties for electronics as thermal interface and packing material. Overall, this work put forwards an effective approach to disperse h-BN and paves the way in developing high-performance thermal interface materials.