Low-dielectric polyimide composite films with enhanced thermal, mechanical, and hydrophobic properties via silica aerogel integration

Abstract

This study investigates the morphological, thermal, dielectric, mechanical, and surface properties of polyimide/silica aerogel (PI/SA) composite films with varying SA content of 3–10 wt%. Nitrogen adsorption/desorption isotherm analyses confirmed the mesoporous structure of SA, exhibiting a high specific surface area (241.1 m²/g) and an average pore size of 34.9 nm. Electron microscopy and energy dispersive spectroscopy mapping revealed uniform dispersion of SA within the PI matrix. Thermogravimetric analysis indicated that PI/SA composites exhibited enhanced thermal stability, as evidenced by increased thermal decomposition temperature and residual char content at 800 °C with higher SA loading. Differential scanning calorimetry analysis demonstrated a slight increase in the glass transition temperature due to the restricted PI chain mobility by the uniform dispersion and interfacial interactions of SA with an intrinsically robust silicate framework. Dielectric property evaluations revealed a significant reduction in dielectric constant, from 3.02 (neat PI) to 2.16 (composite with 10 wt% SA), attributed to the introduction of nanoscale voids within the SA framework. The mechanical properties showed an increase in tensile strength and elastic modulus up to 7 wt% SA, followed by a decrease at 10 wt% due to partial filler agglomeration. Additionally, contact angle measurements indicated improved hydrophobicity with increasing SA content, suggesting enhanced moisture resistance. These findings demonstrate the potential of PI/SA composite films for advanced microelectronic and insulation applications requiring low dielectric properties, high thermal stability, and improved hydrophobicity.