Thermally conductive particle-filled polymer composites have thermal management applications. They can be easily processed and have enhanced thermal conductivity that originates from the fillers. Numerous nanoparticles can be used in their preparation, but dielectric ceramic particles such as boron nitride (BN) are becoming more popular. This is because the resulting thermally conductive composites can simultaneously provide electrical insulation in electronic devices and equipment. Reporting inNanotechnology, researchers present a polymerization technique to prepare BN-based polymer nanocomposites.

Most methods for the preparation of BN-based polymer nanocomposites involve the addition of BN nanoparticles into a commercial polymer matrix or curable thermosetting pre-polymers. However, in situ polymerization can be a promising technique as it has a couple of advantages. First, the as-grown covalently bonded polymer chains guarantee strong interaction between the nanoparticles and the polymer matrix. Second, the as-grown polymer chains may significantly suppress the nanoparticle aggregation and result in excellent nanoparticle dispersion and reduced filler-to-filler interaction.

Enhancing thermal conductivity

A multidisciplinary team comprising researchers from the Shanghai Jiao Tong University and City University of Hong Kong have collaborated to design an approach. This starts with directly growing polystyrene (PS) macromolecular chains on the surface of functionalized BN nanospheres (BNNSs) via reversible addition fragmentation chain transfer (RAFT) polymerization. This is followed by hot-press molding. The thermal conductivity enhancement of the nanocomposites reaches 1375% when the St/BN feeding ratio is 5:1.

Thermal recyclability

In addition, the BNNSs@PS nanocomposites exhibit excellent dielectric properties with a weak dependence on frequency, as well as possessing a desirable low dielectric loss. The processability of PS and the spherical morphology of the BNNSs leads to great thermal recyclability. This makes the current nanocomposites even more attractive for practical industrial applications than thermosetting composite materials. The methodology presented here can serve as a general route for the preparation of thermally conductive, electrically insulating and melt-processable polymer nanocomposites.

The researchers presented their work in the journalNanotechnology 26 015705.