Phase separation dynamics in the presence of surfactant molecules with an asymmetric shape

Abstract

We investigate the dynamics of phase separation processes in the presence of added surfactant molecules with an asymmetric shape, e.g., surfactant molecules with asymmetric hydrophilic/hydrophobic sizes, or block copolymers with asymmetric compositions of subchains. Upon adsorption onto interfaces, such asymmetric surfactant molecules produce a spontaneous curvature of interfaces. The analysis is based on the hybrid model, with which one can investigate the macroscopic phase separation phenomena while keeping some essential molecular features of the surfactant. Computer simulations are performed using the hybrid model and we found a spontaneous morphological change from a bicontinuous structure to a globular structure during the phase separation process. Such a morphological change is caused by the spontaneous curvature of the interfaces where the surfactant molecules are adsorbed. A simple argument to explain such a phenomenon is also presented.

A facile preparation of highly interconnected macroporous PLGA scaffolds by liquid–liquid phase separation II

“…The interconnected pore sizes of the scaffold prepared without diblock copolymers were, in the early stages (!2 min), not smaller than those of the scaffolds prepared with diblock copolymers. However, after 10 min the pore size of the PLGA/PLLA scaffolds gradually increased, in contrast with the scaffold without diblock copolymers, and after 120 min a uniform macroporous structure were observed, a result arising from the growth of larger structures at the expense of smaller ones [37], as shown in Fig. 5(c).…”

Systems Involving Surfactants

“…In particular, the phase separation kinetics at the presence of surfactants has attracted much interest. It was mostly investigated in two dimensions by Langevin simulations [217,218,219,220,221]. The differences lie in the particular form of the Ginzburg-Landau model, and in the dynamical system which is examined.…”

“…It was mostly investigated in two dimensions by Langevin simulations [217,218,219,220,221]. The differences lie in the particular form of the Ginzburg-Landau model, and in the dynamical system which is examined.…”

“…Therefore they work with a hybrid models, which treats the surfactants as particles, and the difference of oil and water density by a Ginzburg-Landau field [220]. Related models due to the same authors represent all particle densities by continuous fields, but include long range interactions between the surfactants, or extend the original hybrid model in other ways [221].…”

Kinetics of Phase ordering in Microemulsions and Micellar Solutions

“…Kawakatsu et al 46 have also studied phase separation in immiscible binary mixtures in the presence of surfactant molecules of asymmetric shape using the hybrid model. They observed a spontaneous morphological change from a bicontinuous structure to a micellar structure during the phase separation process which gives rise to the formation of a amphiphilic monolayer at the oilwater interface.…”