Ultrasonic Intercalation of Gold Nanoparticles into a Clay Matrix in the Presence of Surface-Active Materials. Part II: Negative Sodium Dodecylsulfate and Positive Cetyltrimethylammonium Bromide

The influence of two surfactants with different charges, anionic sodium dodecylsulfate and cationic cetyltrimethylammonium bromide, on the intercalation of preformed Au nanoparticles into a clay matrix under ultrasonic treatment has been investigated. Surfactant addition has been used to modify the active surface area of Na(+)-montmorillonite and to change the interlamellar space between the clay layers. Then, intercalated surfactant in clay composites has been replaced by Au nanoparticles under sonication. The presence of the anionic surfactant in the clay matrix permits intercalation of Au nanoparticles only at the edge of the clay. The cationic surfactant has a very strong interaction with the negatively charged clay surface subsequently blocking the penetration of large amounts of Au nanoparticles during sonication. Therefore in both cases they do not enable full penetration of the clay layers by Au nanoparticles in contrast to previous findings for nonionic surfactants.