POSS with Vinyl and Epoxy Group to Enhance Dielectric and Thermal Properties of Bismaleimide–Triazine Resins

Bismaleimide–triazine (BT) resins are widely utilized in various applications, with ongoing efforts to enhance their performance. In this work, a partially epoxidized polyhedral oligomeric silsesquioxane (PEOVS) containing vinyl and epoxy groups was successfully synthesized, and BT/PEOVS nanocomposites were prepared by blending PEOVS with BT resin. The results revealed that the unique structure of PEOVS significantly improved its dispersion within the resin matrix and enhanced the overall properties of the BT resin. The curing mechanism and properties of BT/PEOVS nanocomposites, with weight ratios of 99.5/0.5, 99/1, 98.5/1.5, 98/2, and 96/4, were analyzed using Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and dielectric measurements. The addition of PEOVS markedly improved the dielectric performance, with a 2% PEOVS content achieving a dielectric constant of 2.39 and a dielectric loss of 0.0036 at 1 MHz. Furthermore, the glass transition temperature and storage modulus were significantly enhanced, with a PEOVS content of 1.5% resulting in a glass transition temperature of 279 °C. The results demonstrate that incorporating PEOVS, featuring dual reactive functional groups, effectively enhances the comprehensive properties of BT resins, providing valuable insights into their modification and practical applications.