Graphene -- Based Nanocomposites as Highly Efficient Thermal Interface Materials

TL;DR

This study demonstrates that a mixture of graphene and multilayer graphene significantly enhances the thermal conductivity of polymer composites, achieving record-high improvements suitable for thermal interface applications.

Contribution

It introduces a cost-effective liquid-phase exfoliation method to produce graphene composites with unprecedented thermal conductivity enhancements.

Findings

Thermal conductivity increased by 2300% at 10 vol.% filler loading.

Achieved thermal conductivity of 14 W/mK at 2% filler loading.

Graphene multilayer composites outperform nanotube-based materials.

Abstract

We found that an optimized mixture of graphene and multilayer graphene - produced by the high-yield inexpensive liquid-phase-exfoliation technique - can lead to an extremely strong enhancement of the cross-plane thermal conductivity K of the composite. The "laser flash" measurements revealed a record-high enhancement of K by 2300 % in the graphene-based polymer at the filler loading fraction f =10 vol. %. It was determined that a relatively high concentration of single-layer and bilayer graphene flakes (~10-15%) present simultaneously with thicker multilayers of large lateral size (~ 1 micrometer) were essential for the observed unusual K enhancement. The thermal conductivity of a commercial thermal grease was increased from an initial value of ~5.8 W/mK to K=14 W/mK at the small loading f=2%, which preserved all mechanical properties of the hybrid. Our modeling results suggest that graphene - multilayer graphene nanocomposite used as the thermal interface material outperforms those with carbon nanotubes or metal nanoparticles owing to graphene's aspect ratio and lower Kapitza resistance at the graphene - matrix interface.