A new siloxane-imide-containing benzoxazine, BZ-A6, has been successfully synthesized. The thermal properties of the polybenzoxazine (PBZ) prepared from BZ-A6 (PBZ-A6) are superior to those of conventional PBZs lacking siloxane groups. The normally brittle PBZs are toughened significantly as a result of adding siloxane-imide moieties. Moreover, the thermal and UV stabilities of the surface free energy of PBZ-A6 are dramatically improved over the conventional bisphenol-A-type PBZ. Siloxane-imide PBZs are more suitable for application as low-surface-free-energy materials that are highly resistant to temperature and UV radiation. PBZ-A6 may also be useful in weather-resistant and self-cleaning coating materials because of its low surface free energy and good thermal and UV resistance.

A series of innovative thermosetting polymer nanocomposites comprising of polysiloxane-imide-containing benzoxazine (PSiBZ) as the matrix and double-decker silsesquioxane (DDSQ) epoxy or polyhedral oligomeric silsesquioxane (POSS) epoxy were prepared for improving thermosetting performance. Thermomechanical and dynamic mechanical characterizations indicated that both DDSQ and POSS could effectively lower the coefficient of thermal expansion by up to approximately 34% and considerably increase the storage modulus (up to 183%). Therefore, DDSQ and POSS are promising materials for low-stress encapsulation for electronic packaging applications.