Reduced graphene oxide (GOr) was prepared according to an elsewhere reported procedure . Briefly, 4 mg/ml GO suspension was added with 12% ascorbic saha histone and stirred for 48 h. After stirring, the resulting suspension was centrifuged and washed in water until complete removal of ascorbic acid. GOr was re-suspended in isopropyl alcohol.
Functionalization of reduced graphene oxide (fnGOr) fillers by APTES was achieved by hydrolysis and condensation reaction between APTES and residual –OH groups on GOr. 1.73 g of APTES and 4.21 g of distilled water were added to GOr prepared by reducing 50 mg of GO. The mixture was sonicated for 2 h. As prepared fnGOr was washed to remove unreacted and irregularly polymerized silane, centrifuged and re-suspended in isopropyl alcohol.
APTES functionalized silica particles (fnSiO2) were prepared by sol–gel reaction of APTES. 1.73 g of APTES was dispersed in isopropyl alcohol with 4.21 g of distilled water. Synthesis in an ultrasonic bath lasted 2 h. The reaction products were used without further processing.