Structure formation in a phase-separating polymer blend with randomly driven particles

Microemulsions in the driven Widom-Rowlinson lattice gas

An investigation of the two-dimensional Widom-Rowlinson lattice gas under an applied drive uncovered a remarkable nonequilibrium steady state in which uniform stripes (reminiscent of an equilibrium lamellar phase) form perpendicular to the drive direction [R. Dickman and R. K. P. Zia, Phys. Rev. E 97, 062126 (2018)10.1103/PhysRevE.97.062126]. Here we study this model at low particle densities in two and three dimensions, where we find a disordered phase with a characteristic length scale (a "microemulsion") along the drive direction. We develop a continuum theory of this disordered phase to derive a coarse-grained field-theoretic action for the nonequilibrium dynamics. The action has the form of two coupled driven diffusive systems with different characteristic velocities, generated by an interplay between the particle repulsion and the drive. We then show how fluctuation corrections in the field theory may generate the characteristic features of the microemulsion phase, including a peak in the static structure factor corresponding to the characteristic length scale. This work lays the foundation for understanding the stripe phenomenon more generally.

Phase transition of a symmetric diblock copolymer induced by nanorods with different surface chemistry

We investigate the phase transition of a symmetric diblock copolymer induced by nanorods with different surface chemistry. The results demonstrate that the system occurs the phase transition from a disordered structure to ordered parallel lamellae and then to the tilted layered structure as the number of rods increases. The dynamic evolution of the domain size and the order parameter of the microstructure are also examined. Furthermore, the influence of rod property, rod-phase interaction, rod-rod interaction, rod length, and polymerization degree on the behavior of the polymer system is also investigated systematically. Moreover, longer amphiphilic nanorods tend to make the polymer system form the hexagonal structure. It transforms into a perpendicular lamellar structure as the polymerization degree increases. Our simulations provide an efficient method for determining how to obtain the ordered structure on the nanometer scales and design the functional materials with optical, electronic, and magnetic properties.

A numerical study of the phase behaviors of drug particle/star triblock copolymer mixtures in dilute solutions for drug carrier application

The complex microstructures of drug particle/ABA star triblock copolymer in dilute solutions have been investigated by a theoretical approach which combines the self-consistent field theory and the hybrid particle-field theory. Simulation results reveal that, when the volume fraction of drug particles is smaller than the saturation concentration, the drug particle encapsulation efficiency is 100%, and micelle loading capacity increases with increasing particle volume fraction. When the volume fraction of drug particles is equal to the saturation concentration, the micelles attain the biggest size, and micelle loading capacity reaches a maximum value which is independent of the copolymer volume fraction. When the volume fraction of drug particles is more than the saturation concentration, drug particle encapsulation efficiency decreases with increasing volume fraction of drug particles. Furthermore, it is found that the saturation concentration scales linearly with the copolymer volume fraction. The above simulation results are in good agreement with experimental results.

Numerical study of the phase separation in binary lipid membrane containing protein inclusions under stationary shear flow

The phase separation of lipids is believed to be responsible for the formation of lipid rafts in biological cell membrane. In the present work, a continuum model and a particle model are constructed to study the phase separation in binary lipid membrane containing inclusions under stationary shear flow. In each model, employing the cell dynamical system (CDS) approach, the kinetic equations of the confusion-advection process are numerically solved. Snapshot figures of the phase morphology are performed to intuitively display such phase evolving process. Considering the effects from both the inclusions and the shear flow, the time growth law of the characteristic domain size is discussed.