Intrinsic Thermal Conductivity of Polyesters with Flexible Segments in Main Chains

Polymers with high thermal conductivity are crucial for addressing the heat dissipation challenges associated with high-performance compact electronic devices. In this work, a series of high thermal conductivity polyesters (PEnx) were synthesized. Their molecular structure is regulated by introducing flexible chains with segments containing n methylene units between 2 and 8. The thermal diffusivity and thermal conductivity of a series of polyesters were studied in relation to their structure. As a result, the thermal diffusivity of polyesters rose from 0.173 to 0.334 mm2 s–1. PEn6 exhibits a thermal conductivity of 0.578 ± 0.0021 W/(m·K), which is 180% higher than PEn2 and three times higher than conventional thermoplastics. The enhanced thermal conductivity can be attributed to the regular molecular structure, which augments heat transfer by mitigating phonon scattering. Thus, it is possible to enhance both the heat absorption and thermal conductivity of the polymer by adjusting the number of methylene groups in the polyester. Meanwhile, the main diffraction peaks of all of the polyesters were around 20°, indicating their semicrystalline nature. Furthermore, PEn6 has excellent thermal stability with a T5% of 396.2 °C, Tmax of 431.1 °C, and residual carbon content of 6.47% at 800 °C.