Thermal Conductivity of Filled Sol-Gel-Derived Hybrid Materials

A novel sol-gel-based hybrid material has been synthesized from organofunctional silanes and aluminates via hydrolysis and condensation reactions. The hybrid material was-in comparison to a silicone rubber-filled with equal amounts of metal filler particles in order to investigate the effective thermal conductivity. The data obtained were compared with theoretical models available in literature to gain understanding of mechanisms responsible for the measured conductivities. Samples were prepared via casting and spin-coating techniques on Teflon (R) and silicon substrates and characterized using laser flash analysis (LFA) and scanning electron microscopy (SEM). It was demonstrated, that the hybrid material with an aluminum content of 40 vol % offers the possibility to achieve an up to five times higher thermal conductivity than filled silicone references. The influence of thermal transition between matrix material and filler was evaluated by a sandwich-layer setup. The results suggest that increased thermal conductivity is also caused by the lower thermal resistance and improved interphase connections within the hybrid material. (C) 2014 Wiley Periodicals, Inc.