TY - JOUR A1 - Majee, Arghya A1 - Bier, Markus A1 - Blossey, Ralf A1 - Podgornik, Rudolf T1 - Charge symmetry broken complex coacervation JF - Physical Review Research N2 - Liquid-liquid phase separation has emerged as one of the important paradigms in the chemical physics as well as biophysics of charged macromolecular systems. We elucidate an equilibrium phase separation mechanism based on charge regulation, i.e., protonation-deprotonation equilibria controlled by pH, in an idealized macroion system which can serve as a proxy for simple coacervation. First, a low-density density functional calculation reveals the dominance of two-particle configurations coupled by ion adsorption on neighboring macroions. Then a binary cell model, solved on the Debye-Hückel as well as the full nonlinear Poisson-Boltzmann level, unveils the charge symmetry breaking as inducing the phase separation between low- and high-density phases as a function of pH. These results can be identified as a charge symmetry broken complex coacervation between chemically identical macroions. KW - Aggregation, Biomolecular self-assembly, Electrostatic interactions, Charged colloids, Colloids, Proteins, Density functional calculations, Polymers & Soft Matter, Biological Physics, Statistical Physics Y1 - 2020 UR - https://doi.org/10.1103/PhysRevResearch.2.043417 VL - 2 IS - 4 ER - TY - JOUR A1 - Mußotter, Maximilian A1 - Bier, Markus A1 - Dietrich, S. T1 - Heterogeneous surface charge confining an electrolyte solution JF - The Journal of Chemical Physics N2 - The structure of dilute electrolyte solutions close to a surface carrying a spatially inhomogeneous surface charge distribution is investigated by means of classical density functional theory within the approach of fundamental measure theory. For electrolyte solutions, the influence of these inhomogeneities is particularly strong because the corresponding characteristic length scale is the Debye length, which is large compared to molecular sizes. Here, a fully three-dimensional investigation is performed, which accounts explicitly for the solvent particles, and thus provides insight into effects caused by ion–solvent coupling. The present study introduces a versatile framework to analyze a broad range of types of surface charge heterogeneities even beyond the linear response regime. This reveals a sensitive dependence of the number density profiles of the fluid components and of the electrostatic potential on the magnitude of the charge as well as on the details of the surface charge patterns at small scales. KW - Density functional theory, Fundamental measure theory, Electrostatics, Partial differential equations, Elementary particle interactions, Electrochemistry, Electrolytes, Interfaces Y1 - 2020 UR - https://doi.org/10.1063/5.0006208 VL - 152 IS - 23 ER -