Preparation and properties of cardanol‐based polybenzoxazine/SiO2 hybrids by sol‐gel technique

A new cardanol‐based benzoxazine monomer containing a hydroxyl group (CBZ) was synthesized and characterized by FT‐IR and 1H NMR spectroscopy. The formation mechanism of cardanol‐based polybenzoxazine/SiO2 hybrids from CBZ and tetraethoxysilane (TEOS) by sol‐gel technique was invested by FT‐IR analysis. FT‐IR and SEM confirmed that there were many SiO2 particles formed and embedded in the cardanol‐based polybenzoxazine. A phase separation occurred when the ratio (wt) of TEOS to CBZ was not less than 3 : 5. TGA results illuminated the thermal stability and char yield of cardanol‐based polybenzoxazine could be enhanced due to the formation of SiO2 particles in the polybenzoxazine matrix. Incorporation of SiO2 could improve the surface de‐wetting and anti‐ultraviolet properties of the films.