Counterion effects on hexadecyltrimethylammonium surfactant adsorption and self-assembly on silica

摘要: Combining optical reflectometry and atomic force microscopy (AFM), we have studied the effects of surfactant counterion on adsorption isotherms, kinetics, layer structure for cationic hexadecyltrimethylammonium (C16TA+) surfactants negatively charged silica surfaces. The kinetics suggest that mechanism changes at critical micelle concentration (cmc). A change in is also suggested by differences observed state interfacial self-assembly either side cmc. Above cmc, increasing binding affinity (from chloride to bromide) increased surface excess approximately 60% changed adsorbed from aggregates with circular projections wormlike micelles. addition 10 mM KCl or KBr both counterions. Below has only a small effect layer, the...