Low Dielectric Polymers with High Thermal Conductivity for High-Frequency Applications

Low dielectric polymers (LDPs) with high thermal conductivity were developed by integrating fused aromatic mesogenic units with silane and siloxane functionalities through hydrosilylation polymerization. The molecular design combines low-polarizable silane moieties and octavinylsilsesquioxane (OVS) with mesogenic aromatic building blocks, enabling reduced dipole density and enhanced molecular organization within the polymer matrix. As a result, the resulting LDPs exhibited an ultralow dielectric permittivity (Dk = 1.79) and dielectric loss (Df = 0.004) over the frequency range of 1–10 GHz. Simultaneously, the ordered molecular packing facilitated efficient phonon transport, resulting in a high thermal conductivity of 0.89 W m⁻¹ K⁻¹. Thermal and structural analyses revealed a distinct cold-crystallization behavior that induced significant reorganization of the molecular packing structure. The increase in crystallinity influenced both dielectric and thermal transport properties, demonstrating a strong correlation between molecular organization and macroscopic performance. These findings provide insight into the structure–property relationships governing dielectric polymers and present an effective molecular design strategy for advanced high-frequency electronic materials. This work was supported by the BK Four Program and Bilateral Exchange Program (RS-2026-25442827).