Fabrication and characterization of low dielectric nanocomposites based on thermotropic liquid crystalline polyester and octaphenyl-polyhedral oligomeric silsesquioxane

This study explores the effects of octaphenyl-polyhedral oligomeric silsesquioxane (POSS) nanofillers on the structure and properties of thermotropic liquid crystalline polyester (TLCP) nanocomposites, focusing on their morphological, thermal, rheological, mechanical, hydrophobic, and dielectric behavior. Electron microscopic analyses confirmed the efficient dispersity of octaphenyl-POSS in the TLCP matrix, while vibrational spectroscopy identified molecular interactions between the two components. X-ray diffraction revealed thinner crystal formation and increased interchain distances of the TLCP matrix with higher POSS content. Thermal analysis showed that melt-crystallization and glass transition temperatures increased with POSS loading, while the melting temperature decreased, indicating improved melt processability. Despite this, the nanocomposites retained excellent thermal stability. Rheological tests demonstrated non-Newtonian shear-thinning behavior, with increasing viscosity and elastic moduli as POSS content rose. Mechanical properties showed a slight decline in bending strength and elastic modulus, but the nanocomposites maintained adequate strength for engineering applications. Hydrophobicity improved, with water contact angles increasing from 77.4 degrees to 90.8 degrees. Notably, the dielectric constant of the nanocomposites decreased from 3.05 for neat TLCP to 2.78 for the nanocomposite with 20 wt% POSS. Overall, the octaphenyl-POSS-reinforced TLCP nanocomposites possess enhanced thermal, hydrophobic, and dielectric properties, making them promising materials for advanced printed circuit board materials in electronic and communication applications.Highlights Octaphenyl-POSS improved thermal, hydrophobic, and dielectric properties of TLCP. SEM/EDS confirmed good POSS dispersion; minor agglomeration at high loadings. FT-IR identified specific interactions between POSS and TLCP matrix. Higher POSS boosted Tmc and Tg, slightly reduced Tm with thinner crystals. Enhanced hydrophobicity and low dielectric constant suit communication devices.