Experimental and Molecular Simulation Study on the Effect of γ-Aminopropyl Triethoxysilane-Modified Nano Silica on the Mechanical and Dielectric Properties of Polyimide Composites

The synthesis of polyimides with low dielectric constants, high wear resistance, and excellent mechanical properties is crucial to expanding their applications in aerospace and microelectronics. This study employed γ-aminopropyl triethoxysilane to modify the surface of silica, yielding a modified silica/polyimide nanocomposite (KSPI). Molecular dynamics simulations were conducted to evaluate the performance of the KSPI, incorporating the microstructural morphology and interface interaction energy changes. Results demonstrated that adding 0.5 wt.% APS-modified silica improved interfacial bonding, as well as mechanical and tribological properties. Compared with pure polyimide, the tensile strength of KSPI increased by 35.99%, whereas the dielectric loss and wear rate decreased by 52.4% and 54.03%, respectively. Simulations comparing KSPI and silica/polyimide systems revealed a 24.15% reduction in the solubility parameter similarity coefficient R and a 77.02% decrease in the free volume for KSPI, indicating superior compatibility owing to its reaction with silica hydroxyl groups to form Si  O  Si bonds, reduce hydrophilicity, and inhibit agglomeration. γ-aminopropyl triethoxysilane modification improves silica dispersion, enhancing the thermal resistance, tensile mechanical properties, and dielectric properties of the KSPI. This study established a robust preparation method for high-performance polyimide composites and elucidated how interface compatibility regulates polyimide composite performance employing combined theoretical analysis and experimental validation. Highlights γ-aminopropyl triethoxysilane enhances silica and polyimide compatibility. Interface regulation simultaneously improves polyimide mechanical properties. Molecular simulations revealing correlations between interface and performance. The modified composite exhibits higher thermal stability and lower dielectric loss.