Very long-range attractive and repulsive forces in model colloidal dispersions
Instituto de Energías Renovables, Universidad Nacional Autónoma de México (U.N.A.M.),
2 Instituto de Física, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, S.L.P., Mexico
a Present address: CONACyT - Centro de Ingeniería y Desarrollo Industrial (CIDESI), Av. Playa Pie de la Cuesta 702, Desarrollo San Pablo, 76125 Querétaro, Qro., Mexico.
b e-mail: firstname.lastname@example.org
Received in final form: 16 July 2018
Published online: 28 January 2019
Experiments with polymer latex solutions show the coexistence of order-disorder structures of macroions. Because of the large macroions’ sizes, this order–disorder phase coexistence imply the existence of very long-range attractive and repulsive forces, which cannot be explained in terms of conventional direct interaction potentials, which are short-range. Here, we apply an integral equations theory to a simple model for colloidal dispersions, at finite concentrations, calculate the particles distribution functions and the involved effective forces. We find very long-range attractive and repulsive forces among the like-charged macroions. The distribution functions are in qualitative agreement with experimental results. The origin of these forces are discussed in terms of an energy–entropy balance.
© EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature, 2019