Coalescence-Induced Coalescence and Dimensional Crossover during the Phase Separation in Ternary Surfactant/Polymer/Water Mixtures

Abstract

We studied the separation process in the ternary mixtures of nonionic surfactant (C(12)E(6), hexaethylene glycol monododecyl ether), polymer (PEG = poly(ethylene glycol)), and water. The separation process of PEG/water rich domains from the surfactant rich matrix was observed by the optical microscopy. From the morphological analysis, we determined the size of the domains as a function of time. On this basis we identified a dominating mechanisms of domains growth, that is the coalescence-induced coalescence mechanism. The coalescence (collision) event of two droplets induces a flow or a change of concentration distribution around droplets which pushes other droplets together inducing further growth. We also observed the evaporation-condensation (Lifshitz-Slyozov) mechanism of growth, but it did not affect the growth of large domains appreciably. We determined two regimes of the coalescence-induced coalescence associated with the dimensionality of the system. When the domains were smaller or comparable in size to the sample thickness we observe a three-dimensional growth. When the domains became larger than the sample thickness, a two-dimensional growth was observed. In the first regime, the size of the domains, L(t), grew linearly with t, while in the second regime, L(t) approximately t(0.3). In the binary, surfactant/water system, water domains grew by the geometrical coalescence-induced coalescence as L(t) approximately t in three dimensions.

The effect of macromolecular crowding on mobility of biomolecules, association kinetics, and gene expression in living cells

“…The possible explanation of the hindering effect of the lmwPEG solutions, as suggested by Hou et al [93], are depletion interactions leading in surfactant solutions to the phase separation [94][95][96][97] or in solution of DNA leading to the condensation of DNA [93,98]. From above we deduce that the solutions of the flexible, polyethylene glycol like polymers may not be preferable as in vitro models to study the influence of cellular crowding on the in-cell processes.…”

Phase Separation in Binary Polymer/Liquid Crystal Mixtures: Network Breaking and Domain Growth by Coalescence-induced Coalescence

“…The larger osmotic pressure appears in the domain of larger curvature, and thus, when such a domain touches the large one, the flow of material goes from the smaller to the larger domain. Interestingly, the preferential wetting of the glass by liquid crystal precludes the dimensional crossover observed previously 12 for the surfactant/water mixtures. In this work, we carefully analyzed the morphology evolution during the phase separation process in the binary liquid crystal/polymer mixture (8CB/PS (4-cyano-4′-n-octyl-biphenyl/polystyrene)) by both light scattering (LS) and optical microscopy (OM) methods.…”

“…Interestingly, the CIC mechanism seems to be universal, not dependent upon the material properties of a particular mixture. It has been observed so far in poly(vinyl methyl)ether and water; 10 -caprolactone oligomer and styrene oligomer; 10 n-dodecyl hexaoxyethylene glycol monoether and water; 12 n-dodecyl hexaoxyethylene glycol monoether, water, and poly(ethylene glycol); 12 poly(methylphenylsiloxane) and polystyrene mixture; 5 isotactic polypropylene and diphenyl ether. 13 Here, we show that the same mechanism of growth occurs in the binary polymer/liquid crystal mixture (8CB/PS (4-cyano-4′-n-octyl-biphenyl/polystyrene).…”

“…Light scattering (LS) experiments − and the direct microscopy observation (MO) − ,, are two popular techniques for studying phase separation. Their combination allows us to observe the separation process in the extended time and length scales, since the LS technique gives good results for domain sizes between 0.5 and 5 μm whereas the OM can be used for domains larger than a few micrometers up to sizes exceeding hundreds of micrometers.…”

Dynamics of Phase Separation in Polymer Blends Revisited: Morphology, Spinodal, Noise, and Nucleation

“…Finally, we would like to point out that CHC model with FHG free energy is not suitable to describe the final stages of phase separation without proper account of hydrodynamic flows 52–54. It has recently been demonstrated55–57 in experiments and that in late stages of phase separation when the bicontinuous network breaks into droplets (which must occur either due to the finite size effect or due to the wetting properties of the bounding walls) the system evolves according to the coalescence‐induced coalescence mechanism 52–54. In this mechanism any process of domains coalescence induces hydrodynamic flow, which pushes other domains towards each other and induces further coalescence events.…”