The Effect of Polar Head Charge Delocalization on Micellar Aggregation Numbers of Decylpyridinium Salts, Revisited

The distribution of charge in an isomeric series of decylpyridinium bromide surfactants is calculated using the AM1 semiempirical quantum mechanical molecular model. The aggregation numbers of the surfactants are shown to increase with a decrease in the residual partial charge in the alkyl tails, suggesting a change in the packing of the surfactants. The critical micelle concentration increases with a decrease in the partial charge of the head groups, indicating increased solubility of the surfactant molecule as charge is more widely distributed throughout the molecule.