High Thermal Conductivity and Low Dielectric Constant of Polyesters Based on Fluorine and Mesogenic Unit.

High thermal conductivity polymeric dielectrics with advanced dielectric properties are urgently demanded in various applications. In this study, a series of thermoplastic polyesters containing different content of fluorine and mesogenic unit in main chains are synthesized utilizing polycondensation. The preferred orientation of liquid crystal can effectively inhibit phonon scattering, and the introduction of fluorine can reduce the polarizability of the polymer and increase the free volume. By introducing the biphenyl mesogenic unit and fluorine into the main chain, its thermal conductivity has been increased to 0.425 Wm−1k−1 from 0.183 Wm−1k−1(the polymer without liquid crystal element), which is 132% higher than that of the liquid crystal polymer without fluorine. In addition, the dielectric constant of polyester decreased to 2.97, and the dielectric loss drops to 8.74 × 10−4. The influence mechanism of two ways on its thermal and dielectric properties is explored. Good thermal conductivity and excellent dielectric properties make potential in the thermal management system and flexible electronics. [ABSTRACT FROM AUTHOR]