Preparation, characterization and thermal properties of organic-inorganic composites involving epoxy and polyhedral oligomeric silsesquioxane (POSS)

Organic-inorganic hybrids comprising epoxy resin and polyhedral oligomeric silsesquioxanes (POSSs) were prepared via in situ polymerization of the diglycidyl ether of bisphenol A (DGEBA) and 4,4'-diaminodiphenylmethane (DDM). The POSSs have an active functional group that takes part in the ring-opening reaction with the oxirane group. The organic and inorganic moieties are joined by covalent bonds. These covalent bonds enhance the compatibility of the inorganic and organic phases. Scanning electron microscope (SEM) analytical results indicate that there was no obvious phase separation between the inorganic and organic phases. The UV/VIS spectrum of the epoxy hybrid demonstrates the excellent optical transparency of the hybrids-the most important characteristic for their application as protective coatings. Thermogravimetric analysis (TGA), X-ray photoelectron spectra (XPS), and nuclear magnetic resonance spectroscopy (NMR) of the char showed that the incorporation of the POSSs into epoxy resin improves the thermal stability of the hybrids.