Final Report Summary - CHARGEDANISOTROPY (Interplay of anisotropy and interactions in charged colloidal systems)
Motivated by the observed intriguing phase behaviour of charged colloidal platelets and nanosheets, we investigate the phase behaviour of ultrathin charged disks by means of Monte-Carlo simulations. The electrostatic interactions are taken into account through an effective two-body interaction potential with the form of anisotropic Yukawa potential that is obtained within formalism of linearised Poisson - Boltzmann. We find that the peculiar angular dependence of this potential leads to a very rich phase behaviour for charged disks. Upon varying density and ionic strength, we recognise eight distinct microstructures, four of which are orientationally disordered. They consist of isotropic fluid, plastic crystal, random stacks and a novel structure of intergrowth texture. Investigating the dynamics in the orientationally disordered structures, we find that random stacks and intergrowth texture exhibit a very slow orientational dynamics, while their translational dynamics is diffusive. This behaviour resembles that of an orientational glass.
The orientationally ordered phases appear at higher densities include two liquid-crystalline phases, i.e. nematic stacks and columnar hexagonal phase and two crystalline phases with fcc-like and hexagonal symmetry. We compare our obtained phase behaviour with that of Gibbsite and clay particles. We find that our model system agrees with the observed experimental phase behaviour in some regions of explored parameters.
The orientationally ordered phases appear at higher densities include two liquid-crystalline phases, i.e. nematic stacks and columnar hexagonal phase and two crystalline phases with fcc-like and hexagonal symmetry. We compare our obtained phase behaviour with that of Gibbsite and clay particles. We find that our model system agrees with the observed experimental phase behaviour in some regions of explored parameters.
