Inhomogeneity of solute distribution in ionic systems

Abstract

By using video imagery and an image data analyser, the ordering phenomena of polymer latex particles in dilute suspensions have been studied. The micrographs clearly showed the existence of localised ordered structure coexisting with disordered particles, and furthermore, fairly long-lived void structures were noted. The lattice vibrations of the particles on two adjoining lattice planes were shown to be coupled. Lattice defects were also found and the lattice vibration of the particle around the defect was anisotropic. The growth of the localised structure was found to obey the Ostwald ripening mechanism. All these findings validate the existence of an interparticle long-range attraction in addition to the short-range repulsion.

Buckling instabilities of a confined colloid crystal layer

“…A Yukawa interaction was found to give rise to structural features consistent with observations [3]. Pair potentials have also been used to described the dynamics of colloid crystals [4].…”

Surfaces and interfacial water: Evidence that hydrophilic surfaces have long-range impact

“…The latter possibility is given force by observations on colloidal microspheres in aqueous suspension: At volume ratio of ∼ 1%, microsphere suspensions show two coexisting phases, random and crystalloid. In the random phase, thermal motion is of the anticipated magnitude, but in the crystalloid phase, although microspheres are distinctly separated from one another by several micrometers, r.m.s displacements are lower by an order of magnitude [15][16][17]. Thus, the disruptive effects of thermal motion in ordered regions may be less than generally anticipated, and this feature might predispose molecules to long-range ordering.…”

“…The present results anticipate the restriction phase, and give direction toward understanding the genesis of low friction. In the area of colloid chemistry, understanding why even relatively dilute suspensions of colloidal solutes converge into quasi-regular arrays [15][16][17] could reside in the extensiveness of mobility-limited water surrounding these particles. If so, then water organization around charged surfaces could be a key attribute underlying biological and bio-inspired self-organization.…”

An Overview of Polyelectrolytes

“…For more than two decades, however, Ise and co-workers (3-10) have emphasized that there exists some form of long range attractive interaction between macroions that is not consistent with the standard DLVO potential. More specifically, video movies taken through an ultramicroscope clearly showed two distinct regions in a suspension of latex particles; a highly kinetic region in which the particles undergo Brownian motion, and a relatively static ordered region (5,9) which has embedded regions of stable voids (9). Sogami and Ise (77) thus developed a model based on the Gibbs free energy that exhibited a stable minimum at macroion separation distances on the order of several thousand angstroms, as experimentally observed.…”

“…Belloni (77) (9) and γ is a "screening function" that depends upon ^ and the MSA Coulombic screening parameter whose precise form is of no consequence in this discussion. Sogami and Ise (77) approached the macroion-electrolyte ion problem on the same footing as the quantum mechanical description of chemical bonding.…”