Effect of microscopic-ordered structures on intrinsic thermal conductivity of liquid-crystalline polysiloxane

Abstract

Intrinsic insulating and thermal conductive polymers were prepared by synthesizing liquid-crystalline polysiloxanes elastomer (LCPE) with chemical cross-linking (0.83 W/m K and 0.81 W/m K). The microscopic-ordered structures were found in LCPE and considered affording high thermal conductivity. Chemical structures were observed by hydrogen nuclear magnetic resonance spectroscopy (1H-NMR) and fourier transform infrared (FT-IR) spectroscopy. Microscopic-ordered structures were analyzed by polarizing optical microscopy, scanning electron microscope and X-ray diffraction. Thermal conductivities were calculated according to equation: λ = α·ρ·Cp. Thermal properties were researched by differential scanning calorimeter and thermal gravimetric analyzer. The results revealed that LCPE showed high thermal conductivity because of the microscopic-ordered structures existing. The phonon scattering was suppressed and the mean free path of phonon was extended maximally. In addition, phonon conduction path was more complete. Our study provided a useful method to enhance the thermal conductivities of intrinsic thermal conductivity polymer themselves.