Correlation on molecular orientation and thermal conductivity in spacer-tuned side-chain liquid crystalline polyethylene glycols with fixed tail

초록

Liquid crystalline polymers (LCPs) have attracted significant attention as promising candidates for thermal management in electronic applications due to their intrinsic ability to form highly ordered, anisotropic structures that facilitate efficient heat conduction. In this study, we report the synthesis and characterization of side-chain liquid crystalline polymers (SCLCPs) series, P-BMn, incorporating biphenyl-based mesogenic cores with varying alkyl spacer lengths. These polymers were prepared via anionic ring-opening polymerization of epoxyfunctionalized monomers based on polyethylene glycol backbones. The thermal and mesophase behaviors of both monomers and polymers were systematically examined using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X-ray scattering (SAXS/WAXS). All P-BMnpolymers exhibited mesogenic orientation, with the molecular alignment behavior is confirmed to be significantly influenced by the length of the alkyl spacer chains. Importantly, the thermal conductivity of the P-BMnshowed a clear dependence on spacer length: P-BM4, which contains the shortest spacer, achieved the highest thermal conductivity of 0.61 W/m & sdot;K, indicating that shorter spacers enhance molecular alignment and thermal transport. X-ray analysis revealed that improved alignment and tighter layer packing were key factors contributing to enhanced conductivity. These findings highlight the importance of precise molecular design in optimizing the thermal properties of LCPs, offering insights for the development of advanced polymeric thermal interface materials.

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