Synthesis of a coupling agent containing polyurethane chain and its influence on improving the dispersion of SiO2 nanoparticles in epoxy/amine thermoset

SiO 2 nanoparticles (NPs) were modified with as-synthesized coupling agent containing isocyanate-terminated polyurethane (PUCA) to enhance the interaction between SiO 2 NPs and DGEBA/DDM matrix in purpose of promoting the dispersion condition of the SiO 2 NPs in cured resin. Uniform dispersion of the PUCA-SiO 2 NPs was observed in the cured resin which was in obvious contrast with that of the raw SiO 2 NPs and the IPTS-SiO 2 NPs according to the visible light transmittance and TEM observation. The tensile behaviors of the PUCA-SiO 2 composites were found obviously promoted than that of the raw SiO 2 and IPTS-SiO 2 composites. DMA results showed that the T g of the PUCA-SiO 2 composite was 8.9 °C and 5.8 °C higher than that of the raw, IPTS-SiO 2 composite. SEM observation of the fracture surfaces showed that PUCA-SiO 2 composite possessed the densest crack texture. This work showed that grafting the polyurethane chain to the surface of the inorganic NPs is an effective way to obtain uniform dispersion of the inorganic NPs in resin matrix.