Wertheim perturbation theory: thermodynamics and structure of patchy colloids (original) (raw)
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2015
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The Journal of chemical physics, 2008
We report theoretical and numerical evaluations of the phase diagram for a model of patchy particles. Specifically, we study hard spheres whose surface is decorated by a small number f of identical sites ("sticky spots") interacting via a short-ranged square-well attraction. We theoretically evaluate, solving the Wertheim theory, the location of the critical point and the gas-liquid coexistence line for several values of f and compare them to the results of Gibbs and grand canonical Monte Carlo simulations. We study both ordered and disordered arrangements of the sites on the hard-sphere surface and confirm that patchiness has a strong effect on the phase diagram: the gas-liquid coexistence region in the temperature-density plane is significantly reduced as f decreases. We also theoretically evaluate the locus of specific heat maxima and the percolation line.
A square-well model for the structural and thermodynamic properties of simple colloidal systems
The Journal of Chemical Physics, 2001
A model for the radial distribution function g(r) of a square-well fluid of variable width previously proposed A. Santos, J. Chem. Phys. 101, 2355 (1994)] is revisited and simplified. The model provides an explicit expression for the Laplace transform of rg(r), the coefficients being given as explicit functions of the density, the temperature, and the interaction range. In the limits corresponding to hard spheres and sticky hard spheres the model reduces to the analytical solutions of the Percus-Yevick equation for those potentials. The results can be useful to describe in a fully analytical way the structural and thermodynamic behavior of colloidal suspensions modeled as hardcore particles with a short-range attraction. Comparison with computer simulation data shows a general good agreement, even for relatively wide wells.
Phase Diagram of Patchy Colloids: Towards Empty Liquids
Physical Review Letters, 2006
We report theoretical and numerical evaluations of the phase diagram for patchy colloidal particles of new generation. We show that the reduction of the number of bonded nearest neighbors offers the possibility of generating liquid states (i.e., states with temperature T lower than the liquid-gas critical temperature) with a vanishing occupied packing fraction (), a case which can not be realized with spherically interacting particles. Theoretical results suggest that such reduction is accompanied by an increase of the region of stability of the liquid phase in the (T-) plane, possibly favoring the establishment of homogeneous disordered materials at small , i.e., stable equilibrium gels.
Gas-liquid phase coexistence in colloidal suspensions?
Europhysics Letters (EPL), 2001
PACS. 82.70.Dd -Colloids. PACS. 64.10.+h -General theory of equations of state and phase equilibria. PACS. 64.60.Cn -Order-disorder transformations; statistical mechanics of model systems.
Phase behaviour of pure and mixed patchy colloids — Theory and simulation
Current Opinion in Colloid & Interface Science, 2017
We review the phase behaviour of pure and mixed patchy colloids, as revealed (mostly) by theory and computer simulation. These experimentally-realisable systems are excellent models for investigating the general problem of the interplay between (equilibrium) phase transitions and self-assembly in soft condensed matter. We focus on how liquid-vapour condensation can be preempted by the formation of different types of aggregates, in particular rings, which we argue is relevant to the criticality of empty fluids and network fluids, and possibly also of dipolar fluids. In this connection we also discuss percolation and gelation in pure and mixed patchy colloids. Finally, we describe the rich phase behaviour of (mostly binary) patchy colloid mixtures.
Self-assembly mechanism in colloids: perspectives from statistical physics
Central European Journal of Physics, 2012
Motivated by recent experimental findings in chemical synthesis of colloidal particles, we draw an analogy between self-assembly processes occurring in biological systems (e.g. protein folding) and a new exciting possibility in the field of material science. We consider a self-assembly process whose elementary building blocks are decorated patchy colloids of various types, that spontaneously drive the system toward a unique and predetermined targeted macroscopic structure.