Modification of Al2O3 particles by T-shaped trialkoxylsilylethyl-terminated polydimethylsiloxane oligomers and their applications in thermal interface materials

A series of T-shaped trialkoxysilylethyl-terminated polydimethylsiloxane oligomers with different terminal structures and different degrees of polymerization have been synthesized by a series of reactions and functioned as the surface treatment agent for Alumina particles. The influence of the structure, degree of polymerization, the treatment method of the prepared oligomers , the mass ratio of alumina particles with different particle sizes, the viscosity of the matrix, the ratio between the modifier and the matrix, and the volume fraction of the mixed-size alumina particles on the fluidity and thermal conductivity of the silicone paste were investigated in detail. When a T-shaped trimethoxylsilylethyl-terminated polydimethylsiloxane with a degree of polymerization of 8 was used as the modifier for the mixed-size alumina particles consisting of 70 μm, 3 μm and 0.5 μm blended in a mass ratio of 9: 4: 2 and its dosage is 1/10 mass of the dimethyl silicone oil with a viscosity of 100 mPa.s, a silicone paste filled with 87 vol% hybrid alumina particles with a thermal conductivity of 6.95 W/(m· K) and good fluidity could be prepared. In the 30 W HB-LED heat dissipation application experiment, the results of thermal infrared imaging indicated that compared with the silicone paste filled with 83 vol% alumina with the same compositions while no modifier is used, the surface temperature on the HB-LED chip dropped from 118.2 °C to 79.0 °C. Moreover, the silicone paste with 87 vol% alumina had a higher cone penetration than that without the addition of any modifier. Based on the FT-IR, XPS, and 3D microscopy images of the modified alumina filler, the modification mechanism was briefly discussed. • T-shaped trialkoxylsilylethyl-terminated PDMS oligomers prepared and used as the Al 2 O 3 modification agent. • Pre-treatment of Al 2 O 3 with functionalized polysiloxane enhance the fluidity of silicone paste. • Trimethoxysilylethyl-terminated oligomers increased the dosage of Al 2 O 3 in matrix. • Silicone pastes filled with modified Al 2 O 3 exhibited enhanced thermal performance.