Enhancing Thermal Conductivity in Low Dielectric Polybutadiene via a Liquid Crystal Ordering Effect

Hydrocarbon polymers are ideal dielectric materials in microelectronic industry due to their extraordinarily low dielectric constant (D_k) and dielectric loss (D_f). However, a challenge remains in improving their intrinsic thermal conductivity. This work establishes a novel method to develop hydrocarbon polymers with enhanced thermal conductivity by a liquid crystal (LC) ordering effect. An LC molecule is designed with triphenyl mesogen and styrene end groups (ST38), cross-linking in polybutadiene to form an LC polymer (ST38PB). The exploration of LC arrangement reveals that the formation of well-ordered LC domains is induced by π-π stacking of triphenyl group, with its orientation being fixed by the cross-linking reaction. The LC domains demonstrate exceptional thermal stability, maintaining their structural integrity even at 260 °C. ST38PB exhibits an enhanced intrinsic thermal conductivity coefficient (λ) of 0.62 W m^-1 K^-1, which is 3.4 times that of pristine polybutadiene. Meanwhile, it displays excellent dielectric properties (D_k = 2.40, D_f = 3.3 × 10^-3 at 10 GHz). The use of ST38PB as thermal management materials for chip cooling and dielectric substrates for printed circuit boards is investigated. The findings confirm its promising potential for applications, and this strategy can be further extended to develop other LC-based thermally conductive polymers for demanding high-temperature applications.