High performance epoxy composites modified by a ladder-like polysilsesquioxane

Developing transparent epoxy resins (EPs) with high mechanical properties, thermally stable, and superior dielectric properties is of vital importance for electronics and communication application. Here we synthesized a novel ladder-like polysilsesquioxane containing phenyl and amino groups (N-PPSQ) via a facile co-condensation process for EP modification. The N-PPSQ features a highly regular ladder-like structure with several reactive amino groups anchored, as confirmed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and nuclear magnetic resonance silicon spectroscopy (29Si NMR). Different EP/N-PPSQ composites with optimized additive contents were prepared. Compared to the pure EP, 10 wt% N-PPSQ addition helps to increase the impact strength of EP by a maximal 73 % while simultaneously improving the tensile and flexural properties. With maintained high transparency and enhanced hygrothermal stability, the EP/N-PPSQ composite shows lower dielectric constant and dielectric loss than pure EP. The work demos a fine solution to improving the toughness, dielectric properties and hygrothermal stability without sacrificing the mechanical and optical properties of EP.