Phase change material composites in a clay-like structure featuring GPTMS and butylated epoxy for heat buffering and thermal interface performance

Phase change material (PCM)-based thermal interface materials (TIMs) offer both heat conduction and buffering, but their practical use is hindered by leakage during phase transitions, discontinuous thermal pathways, and insufficient structural stability. Here, we report a clay-like PCM composite engineered by integrating (3-glycidyloxypropyl)trimethoxysilane (GPTMS)-functionalized boron nitride (BN) with a butylated epoxy (BuEP) matrix. GPTMS treatment enhanced interfacial compatibility between BN and lauric acid (LA), enabling efficient latent heat transfer and stable PCM retention. A continuous thermally conductive skeleton was formed by the aligned BN network impregnated with LA, while the BuEP matrix prevented leakage and improved mechanical robustness. The optimized composite achieved high thermal conductivity (5.68 W/m·K), significant latent heat storage (96.43 J/g), and excellent electrical insulation (>10 11 Ω·cm), while maintaining mechanical compliance (elongation ∼69%). These properties translated into superior thermal regulation performance under device-level testing, demonstrating reduced temperature rise and stable operation. This study provides a practical design strategy that simultaneously addresses leakage, discontinuous conduction, and structural instability, thereby broadening the potential of PCM-based TIMs for next-generation electronic systems.