Preparation and characterization of cationic surfactant-intercalated graphite oxide

Various quaternary alkylammonium or alkylpyridinium ion-graphite oxide (GO) intercalation compounds were synthesized. The maximum saturated amount of intercalated surfactant ions into GO was 560 mequiv/100 g GO (0.56 mol/100 g GO) which was much larger than those observed for surfactant-clay compounds and it decreased with the decrease in alkyl chain length. The IR spectrum of surfactant-intercalated GO sample suggested that surfactant ion was bonded to oxygen of the GO via ionic bonding. Four types of interlayer spacings; 2.9 nm, 1.9 nm, 1.6 nm and 1.2 nm were clearly observed for lauryltrimethylammonium ion-GO intercalation compounds, depending on the intercalated amount of surfactant, and structure models for them were proposed. On the other hand, when alkyl chain length increased, intercalation compound in which the surfactant lies as a bilayer was mainly obtained, irrespective of the density of surfactant in the layer of GO. The results in this study strongly suggest that it is possible to control the space occurring between the surfactants in GO layers in a wide range by changing the type and amount of surfactant added. (C) 1999 Elsevier Science Ltd. All rights reserved.