Self-assembly and co-assembly of block polyelectrolytes in aqueous solutions. Dissipative particle dynamics with explicit electrostatics

This topical review outlines the principles of dissipative particle dynamics (DPD) and discusses its use for studying electrically charged systems - particularly its application for investigation of the self-assembly of polyelectrolytes in aqueous solutions. Special emphasis is placed on DPD with incorporation of explicit electrostatic forces (DPD-E). At present, this empowered method is being used by only a few research groups and most studies of polyelectrolyte self-assembly are based on the 'implicit solvent ionic strength' approach which completely ignores electrostatics. The inclusion of electrostatics in the DPD machinery not only complicates the calculations and considerably slows down the simulation run, but it also generates some problems of primary importance that have to be solved prior to employing DPD-E to study practically important systems. In the introductory parts, we describe the principles of DPD-E, analyse all the problematic issues and show how they can be resolved or overcome. The later parts demonstrate the successful application of DPD-E. We discuss papers that study the self-assembling behaviour of two different practically important systems and show that they not only closely reproduce all the decisive features of the behaviour, but also reveal new details that are difficult to access for experimentalists. The topical review shows that the tedious calculations are worthwhile: (1) DPD-E simulations are concerned with the true principles of the behaviour of polyelectrolyte systems and therefore provide reliable data and (2) the practically important advantage of computer simulations, i.e. their predictive power (at the level of the employed coarse-graining), which is a questionable aspect in simulations that use physically impoverished models, is not endangered in the case of DPD-E.