Molecular Orientation\nand Thermal Conductivity in\nLiquid Crystalline Epoxy Resins by Anionic Ring-Opening Polymerization

High thermal conductivity polymers\nattract significant scientific\ninterest for their potential in various fields. However, practical\napplications remain limited due to their insufficient performance.\nLiquid crystalline epoxy resins (LCEs) exhibit high thermal conductivity\ndue to a well-aligned molecular orientation and strong intermolecular\ninteractions. In this study, we demonstrated BPR<i><sub>n</sub></i> as a novel LCE system for improving thermal conductivity\nthrough enhanced molecular orientation. The BPR<i><sub>n</sub></i> was designed by introducing various alkyl chains into the\nbiphenyl moiety, and anionic ring-opening polymerization was carried\nout by using 2-methylimidazole as the curing agent. Thermal properties\nwere investigated using differential scanning calorimetry (DSC), thermogravimetric\nanalysis (TGA), thermomechanical analysis (DMA), and thermal conductivity\nmeasurements. The microstructure of BPR<i><sub>n</sub></i> was examined through polarized optical microscopy (POM) and X-ray\nscattering analysis. Changes in physical properties, including orientation\nstructures with varying chain lengths, were investigated, and the\npotential of electronic materials was confirmed based on thermal conductivity.\nBPR<sub>8</sub>, with the longest alkyl spacer, showed a significantly\nhigh thermal conductivity (0.53 W/m·K). The temperature change\nof BPR<i><sub>n</sub></i> on a 150 °C hot plate was\nobserved by using a thermal imaging camera to demonstrate the practical\nimprovement in thermal conductivity.