High-Efficiency Improvement of Thermal Conductivity for Polydimethylsiloxane Composites from Fabricated Sesame Cracker-Like Hetero-Structured Fillers Based on In-Situ Welding

Thermal conduction for electronic equipment has grown in significance in view of the booming of 5G era. Optimizing material thermal characteristics is regarded to be critical to increasing electronic device performance. Along with this, the construction of heterostructure provides an effective means of influencing thermal transport mechanisms. Herein, “in-situ welding” method is developed to prepare “sesame cracker”-like hetero-structured alumina microsphere@boron nitride nanosheet (f-A@B) thermally conductive fillers. And the thermally conductive f-A@B/polydimethylsiloxane (PDMS) composites are obtained by means of doctor blade coating. When the mass fraction of f-A@B is 30 wt%, the f-A@B/PDMS composite presents the optimal thermal conductivity coefficient of 3.72 W m−1 K−1, represented a 1279 % increase compared to the pure PDMS (0.27 W m−1 K−1). A highly thermal conductivity depends largely on the ordered assembly of fillers in composites. The modified Hashin-Shtrikman (MHS) model verify and explain the experimental results, suggesting the reduced filler-to-filler interfacial thermal resistance accounts for the construction of f-A@B heterostructure. The contact thermal resistance (0.0997 m2 K W-1) of this composite can be decreased efficiently by ~12.5 % than A@B/PDMS directly mixed system. Meanwhile, the as-prepared composites exhibit exceptional volume resistivity up to 2.2 × 1013 Ω cm, which is 4 orders of magnitude higher than the critical resistance for electrical insulation (109 Ω cm). Furthermore, the f-A@B/PDMS composites retain remarkable mechanical properties like pure PDMS plus notable thermal stability and reliability. The composites with superior thermal conductive and electrical insulating properties may open up future prospects in electrical packaging and thermal management.