On the dynamic character of "ordered" structure in polymer latex suspensions

Abstract

A detailed microscopic study on polymer latex suspensions has been carried out. Particular emphasis is placed on the dynamic aspects of the ordered structure by using video imagery and an image data analyzer. This technique allows us to treat a large number of particles (usually 200 particles) over a longer time span, which improves considerably the reliability of the data compared to the almost "manual" treatment for a very limited number of particles as in our previous papers. The variation (actually disappearance) of localized ordered structures is demonstrated. The particles in the border regions between the ordered and disordered structures are also shown to be dynamic. The thermal motion of the particles in the ordered regions was found to be substantial at low concentrations. The thermal motion was found to be considerable at 10 and 60 °C but not so pronounced at 30 °C, which can be understood when the temperature dependence of the dielectric constant of water is taken into consideration. The motion of the particles in the coexisting ordered and disordered structures is compared. The results of the dynamical study indicated that a clear distinction must be made between the two coexisting structures, although the ordered structure is far from an ideal lattice.

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

“…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.…”

“…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.…”

Effective interaction of highly charged plates in an electrolyte

“…A possible candidate for such a framework has been proposed by one of the present authors [13]. The new linearized theory, which is based on the Gibbs free energy, explains the existence of long-range Coulombic attraction between highly-charged macroions, and describes qualitatively the ordering phenomena of spherical macroions [13,14] and plate macroions in an electrolyte [15]. However, the new framework remains no better than a crude approximation, because the concept of the Gibbs free energy is strictly applicable only to a homogeneous system [16].…”

Adsorption, Desorption, Surface Diffusion, Lattice Defect Formation, and Kink Incorporation Processes of Particles on Growth Interfaces of Colloidal Crystals with Attractive Interactions

“…In such systems, in situ observation of growth interfaces of colloidal crystals by optical microscopy is usually difficult because of high particle concentrations. Although a few exceptions have shown the dynamic character of growth interfaces of colloidal crystals at the particle level and claimed the existence of attractive interactions between particles [56][57][58], these studies involved only in situ observation of cross sections of the growth interfaces; there are no reports on the two-dimensional dynamics of particles on the growth interfaces. Furthermore, particles in the crystals in those studies separated from each other; repulsive interactions were still dominant.…”