2.2.4. Surface Functionalization of Silica Particles

Silica particles (4.0 g) were shaken for 1 h in a mixture of ethanol (40 mL) and an aqueous solution of ammonium hydroxide (640 µL, 25%). After 1 h the corresponding organosilane reagent (200 µL, Am-1, Am-2 or Am-3) was added, then the suspensions were shaken (room temperature, 450 rpm, orbital shaker Vibramax 100, Heidolph NA Llc., Schwabach, Germany) for 24 h, then further organosilane was added (600 µL), and it was shaken for further 48 h. Silica particles were washed with ethanol (3 × 10 mL) using centrifugation (15 min, 10,000 rpm, 5 °C, Z300K, Hermle AG, Gosheim, Germany). The functionalized silica particles were dried on open-air until constant mass.