Grafting polymerization of polyacetal onto nano-silica surface via bridging isocyanate

A method of surface modification of nano-silica by surface grafting of polyacetal (PAc) via bridging toluene 2,4-di-iso-cyanate (TDI) was developed. The resultant grafting rate of up to 79.6% was much higher than that of direct grafting of PAc. Monodisperse nano-silica in polar media was obtained under the optimal experimental condition. The sedimentation experiments showed that the modified nano-particles had good suspension stability in DMF and the monodispersity was demonstrated by AFM image. The modified samples were also characterized by 1H NMR, FTIR and XPS techniques. The experimental results indicate that the modification of nano-silica by surface grafting via bridging TDI is a powerful approach to improve its dispersion property.