Effect of the conformation of the hydrophobic long chains on ionic association in aqueous solution. Theoretical study of the poly(methyleneammonium) acetate system

Abstract

Potential-energy curves have been calculated in a vacuum and in aqueous solution for the R—NH⁺₃…^–OOC—CH₃ systems, where R is a polymethylene chain with ten, twenty and thirty carbon atoms. A parameter which takes into account the degree of coiling was introduced; the solvent effect was estimated by a continuum model taking into account the ellipticity of the cavity.

It was found that, unlike the gas phase, in solution there is a strong correspondence between the conformation of the aliphatic chain and the shape of the dissociation curve.

It was also found that in a random-coil chain conformation some stabilization of the ion-pairs is possible.