Mechanism and properties of coloured nanoscale SiO 2 prepared from silica and reactive dyes

KH 560‐modified SiO 2 was prepared using tetraethyl orthosilicate ( TEOS ) and γ‐(2,3‐epoxypropoxy) propytrimethoxysilane ( KH 560) by the sol–gel method and then coloured with CI Reactive Blue 4 (X‐ BR ) to prepare coloured nanoscale SiO 2 . The antisolvent performance and the results of cross‐polarisation/magic angle spinning 13 C nuclear magnetic resonance and Fourier transform infrared spectroscopy showed that the reaction of X‐ BR with KH 560‐modified SiO 2 is a two‐step process: X‐ BR is firstly adsorbed by KH 560‐modified SiO 2 via van der Waals forces, and then nucleophilic substitution occurs between dichloro triazine and the epoxy group. The grafting ratio of X‐ BR on KH 560‐modified SiO 2 reached 95% under optimum conditions, i.e. a mass ratio of KH 560 to TEOS of 20%, a temperature of 40 °C, a pH of 8.5, and a reaction time of 5 h. X‐ray diffraction analysis and transmission electron microscopy showed that the coloured nanoscale SiO 2 was amorphous, with a mean diameter of 216 nm. Experimental application showed that the coloured nanoscale SiO 2 had excellent stability to solvents and alkaline solution, and the absorptive capacity of the coloured nanoscale SiO 2 in the 200–400 nm region was higher than that of X‐ BR . The light fastness of the coloured nanoscale SiO 2 reached 5–6 grade.