Novel low surface free energy materials of polybenzoxazine/organically modified silicate nanocomposites have been prepared and characterized. The CPC (cetylpyridinium chloride)/ claylo%/poly(3-phenyl-3,4-dihydro-2H-1,3-benzoxazine) (PP-a) material possesses an extremely low surface free energy (12.7 Mj. M-2) after 4 h curing at 200'C, which is even lower than that of poly(tetrafluoroethylene) (22.0 Mj. M-2) calculated on the basis of the threeliquid geometric method. X-Ray photoelectron spectroscopy (XPS) shows a higher silicon content on the surface of the nanocomposites than for an average composition, which implies that the clay is more preferentially enriched on the outermost layer. In addition, the glass transition temperature (Tg) of the polybenzoxazine (PP-a) in the nanocomposite is 22.6'C higher and its thermal decomposition temperature is also 31.5'C higher than the pure PP-a. This finding provides a simple way to prepare low surface energy and high thermal stability materials.