The glass transition of charged polymer colloids

Abstract

The glass transition dynamics of polymer micronetwork colloids. A mode coupling analysis Dynamic and static light scattering is applied to concentrated suspensions of a new species of charged colloidal suspensions with a low refractive index. The polymer colloids which were obtained by polymerizing perfluorobutylacrylate could be index matched in a water/glycerol mixture. At volume fractions ⌽ greater than 0.22 a glass transition can be observed, which is manifested by the nondecaying components of the intermediate scattering functions. The intermediate scattering functions for a supercooled liquid sample and the predictions of the mode-coupling theory for the ␤ relaxation are compared over a large Q range. By using an exponent parameter ϭ0.76 a good agreement between theory and experiment can be obtained.

A Multipurpose Instrument To Measure the Vitreous Properties of Charged Colloidal Solids

“…Liquid-like static structure factors with heights of the first maximum well above 3 have been observed. Similar findings were reported by Härtl et al (6) in static light scattering (SLS) experiments on perfluorinated particles. A split in the second peak of the structure factor was observed by Kesavamoorthy et al (11) for mixtures of differently sized spheres.…”

“…For hard spheres the glass transition (GT) was reported to occur at a packing fraction of GT = 0.57-0.58, close to loose random packing (5). Experimental reports (6) and theoretical expectations (7) for charged spheres interacting via a long-range screened Coulomb potential show much lower values that strongly depend on the screening with added electrolyte. In fact, fully deionized Laponite plates in water show signatures of a glass at packing fractions around 0.01 (8).…”

“…Recently, the focus started shifting toward the more complicated case of charged glasses, where apart from geometrical constraints (22) and hydrodynamic interactions (23), the long-ranged Coulomb repulsion also has to be addressed both in modeling (24) and in using appropriate experimental conditioning procedures (7,25). Here, Härtl et al (6) measured the dynamic structure factor in single-component spherical systems and Bonn et al (8) in charged plates. In both cases two-step decays of the intensity autocorrelation function were observed.…”

Deconstructing the glass transition through critical experiments on colloids

“…Further studies on the formation of these so-called Wigner glasses examined various aspects of structure [216][217][218], dynamics [219] as well as cooperative motion [220,221]. These glasses have also been investigated within the context of the mode coupling theory (MCT) [222] and more recently, the random first-order transition theory (RFOT) [223]. A majority of colloid experiments aimed at verifying specific theoretical predictions, on the other hand, have been performed on hard sphere-like colloids, using dynamic light scattering [224] as well as microscopy techniques and we review these in detail below.…”

Liquid-glass transition in charge-stabilized colloidal dispersions

“…In spite of this brilliant success of RMSA, comparatively less works are reported on applying the technique to more concentrated charged colloidal dispersions (77 > 0.15). Study on these latter dispersions is both an important and a worthwhile attempt since it affords an understanding of the mystery of the liquid-glass phase transformation whose occurrence was observed to fall into the range of 77 > 0.2 (2,9). This paper reports calculations which show clearly that the RMSA is equally useful for chargestabilized dispersions described by high concentrations (r?…”