Re-entrant phase behaviour of network fluids: A patchy particle model with temperature-dependent valence

Abstract

Abstract:We study a model consisting of particles with dissimilar bonding sites ("patches"), which exhibits self-assembly into chains connected by Y-junctions, and investigate its phase behaviour by both simulations and theory. We show that, as the energy cost epsilon(j) of forming Y-junctions increases, the extent of the liquid-vapour coexistence region at lower temperatures and densities is reduced. The phase diagram thus acquires a characteristic "pinched" shape in which the liquid branch density decreases as the temperature is lowered. To our knowledge, this is the first model in which the predicted topological phase transition between a fluid composed of short chains and a fluid rich in Yjunctions is actually observed. Above a certain threshold for epsilon(j), condensation ceases to exist because the entropy gain of forming Y-junctions can no longer offset their energy cost. We also show that the properties of these phase diagrams can be understood in terms of a temperature-dependent effective valence of the patchy particles.

Selective transformations between nanoparticle superlattices via the reprogramming of DNA-mediated interactions

“…However, it is significantly more challenging to control lattice transitions between different phases, crystallographic symmetries or morphological states, wherein global structural reorganization is required. One tentative example is to exploit peculiar temperature-dependent interactions, such as reentrant liquid-solid-liquid transitions, as recently studied theoretically 18,19 and experimentally 20,21 .…”

Closed-loop liquid-vapor equilibrium in a one-component system

“…This orientational order can also appear as a second phase transition for values of y < 0.5 where the LVE occurs. The topology of the empty liquid phases is well understood [9][10][11][12]. At low temperature (where the empty liquid regime occurs) and not too low density almost all the A patches are participating in a bond, and the liquid phases then can be described as a network fluid composed of (almost) straight chains of spheres linked by sequences of AA bonds.…”

“…These systems sometimes present reentrant condensation induced by variations of salt concentration [5,6]. The mechanisms involved in the condensation and the dependence of the reentrant behavior with temperature are not well understood, but it is likely that specific (patchylike) interactions [7,8] play an important role.Given the complexity of both kinds of problems, selfassembly of patchy colloids and the phase behavior of protein solutions, it seems important to study simple models of the patchy particles in order to understand the influence of the numbers of patches and their distribution on the phase behavior and aggregation mechanisms of complex systems.Recently it has been found that patchy models with two types of patches, A and B, in which only A-A and A-B interactions are attractive, can exhibit liquid-vapor equilibria (LVE) with liquid phases behaving as "empty liquids" [9][10][11]. For these systems the term "empty liquid" [4] refers to the fact that at low temperatures the density of the liquid phase ρ L on the binodal becomes very small at low temperature.…”

Molecular theory for the phase equilibria and cluster distribution of associating fluids with small bond angles

“…There has also been an extensive number of theoretical and simulation studies on the thermodynamics, phase behavior, and self-assembly of patchy colloid fluids. [8][9][10][11][12][13][14][15][16][17][18][19][20][21] Patchy colloids are typically modeled using Wertheim's first order perturbation theory (TPT1) and a potential model for conical association sites introduced by Bol 22 and later Chapman 23 that became widely used in the patchy colloid community after Kern and Frenkel 24 introduced this potential as a primitive model for patchy colloids. a) Author to whom correspondence should be addressed.…”