Effect of adsolubilized solutes on 2-D structure of cationic admicelles

The effect of adsolubilized solutes possessing different polarities and loci of adsolubilization on the two-dimensional structural transformation of cationic admicelles was studied. Cetylpyridinium chloride (CPC) was used to form admicelles on mica surfaces below its critical micelle concentration (∼80% of CMC). The studied solutes include n-hexane, naphthalene, diphenylmethane, diphenylether, diphenylamine and 4,4′-bipyridine. In the presence of adsolubilization, it was concluded that both hydrophobic interactions and cation-π binding tend to induce cationic admicelle structural transformation from full-cylinders to bilayer. There is evidence that the effect of the hydrophobic interactions is possibly stronger than the cation-π binding. In addition, the influence of adsolubilized solutes (in the same molecular series) on the admicelle structure should be examined by comparing solute dipole moment instead of solute aqueous solubility.