With the rapid advancement in electronics systems, there is a high demand for components that achieve size, weight, power, and cost reductions (SWaP+C). This need for greater miniaturization has contributed to a dramatic increase in heat generation within these systems, resulting in compromised performance, sacrificed reliability, and reduced device lifecycle.1 In addition, with ever-increasing spectral congestion and since electronic products incorporate faster components operating at higher frequencies than ever before, electromagnetic interference is becoming challenging to mitigate, posing a major concern for human health and the environment.2 It is therefore highly critical to develop high-performance material systems that can concurrently mitigate the detrimental effects of thermal and EM radiation while maintaining the highly desired SWaP+C configurations.
To this effect, we have developed an innovative synthesis strategy involving melt blending, vacuum impregnation, and magnetic-field assisted spin coating to fabricate flexible multicomposite films comprising of FeSi particles (~30-50 Î¼m) and graphene nanoflakes (200-300 nm) confined in a shape-stabilized phase change material (PCM) matrix. In this multifunctional material, the PCM enables efficient heat absorption via the phase change process, the graphene flakes enhance the thermal conductivity to facilitate heat dissipation, and the FeSi particles enhance electromagnetic absorption in the X and Ku bands due to their high magnetization and magnetic anisotropy. With the synergistic effect of graphene and FeSi, the resulting composite displays a thermal conductivity of 0.60-0.75 W/mK, latent heat of 110-120 J/g at 70 Â°C, and excellent EM shielding effectiveness (SE) in the range of 10-60 dB depending on thickness in the range 200 Î¼m to 2 mm (an example is shown in Fig 1). Processing-structure-property correlations of the multifunctional films will be discussed in the context of their percolation threshold.
Research supported by the Commonwealth Cyber Initiative (Grants HV-2Q22-003 and HV-4Q21-002).