Simulation studies of colloidal phase behaviour: beyond effective one-component models
Lead Research Organisation:
University of Bath
Department Name: Physics
Abstract
Colloidal suspensions are a class of fluid in which microscopic particles are dispersed in a liquid solvent. Examples arise in a host of natural and synthetic soft matter systems including micelles, protein solutions, oil-water emulsions, liquid crystals and blood. Technologically, colloidal suspensions feature in applications as diverse as paints, drug delivery systems and lubricants. They are also prevalent in consumer items such as detergents and cosmetics as well as many foodstuffs like mayonnaise. However, in all such systems one issue is key, namely the stability of the suspension, or more generally its phase behaviour.This work will employ computer simulation to study the properties of dispersions of colloidal particles to which much smaller nanoparticles have been added. Such additives have been shown to dramatically change the physical properties of a dispersion, specifically the tendancy of the colloidal particles to phase separate or to aggregate into a gel. This happens because the additive modifies the effective interaction betwen colloid particles. However, a complete understanding of how this happens and exactly how it depends on the colloid-additive and additive-additive interactions is presently lacking for anything other than hard sphere systems. We shall address this issue in the present work using computer simulations of simplified models namely highly size-asymmetric binary fluid mixtures interacting via dispersion and coulomb forces. Until recently, such studies were technically too difficult to perform, but a new simulation method developed by the proposer now offers direct access to problems of real practical interest. We plan to systematically elucidate the effects of various types and concentrations of additive on phase behaviour and to discover the conditions under which exotic self-assembled inhomogeneous phases occurs, such as modulated structures or cluster phases. Such structured phases potentially offer great utility as templates for nanolithography, nanoelectronics, photonic crystals and protein crystallization.
Organisations
People |
ORCID iD |
Nigel Wilding (Principal Investigator) |
Publications
Ashton D
(2010)
Grand canonical simulation of phase behaviour in highly size-asymmetrical binary fluids
in Molecular Physics
Ashton DJ
(2010)
Fluid phase coexistence and critical behavior from simulations in the restricted Gibbs ensemble.
in The Journal of chemical physics
Ashton DJ
(2011)
Depletion potentials in highly size-asymmetric binary hard-sphere mixtures: comparison of simulation results with theory.
in Physical review. E, Statistical, nonlinear, and soft matter physics
Ashton DJ
(2010)
Monte Carlo cluster algorithm for fluid phase transitions in highly size-asymmetrical binary mixtures.
in The Journal of chemical physics
Sollich P
(2011)
Polydispersity induced solid-solid transitions in model colloids
in Soft Matter
Wilding NB
(2009)
Solid-liquid coexistence of polydisperse fluids via simulation.
in The Journal of chemical physics
Description | We have developed new simulation techniques which allow one to study for the first time the phase behaviour of fluids which comprise a mixture of large and very small particles. This is useful because small particle additives can be used to change the properties of systems such as colloidal dispersions. We have used our methods to better understand this effect so that one can in future tailor the phase behaviour of colloidal dispersions. |
Exploitation Route | The methods developed will help allow researchers working in academia and industry to tailor the phase behaviour of colloidal dispersions. |
Sectors | Agriculture, Food and Drink,Chemicals,Pharmaceuticals and Medical Biotechnology |