Coupling between criticality and gelation in “sticky” spheres: a structural analysis

Abstract

We combine experiments and simulations to study the link between criticality and gelation in sticky spheres. We employ confocal microscopy to image colloid-polymer mixtures and Monte Carlo simulations of the square-well (SW) potential as a reference model. To this end, we map our experimental samples onto the SW model. We find an excellent structural agreement between experiments and simulations, both for locally favored structures at the single particle level and large-scale fluctuations at criticality. We follow in detail the rapid structural change in the critical fluid when approaching the gas-liquid binodal and highlight the role of critical density fluctuations for this structural crossover. Our results link the arrested spinodal decomposition to long-lived energetically favored structures, which grow even away from the binodal due to the critical scaling of the bulk correlation length and static susceptibility.

Crystallisation and polymorph selection in active Brownian particles

“…This is intriguing as one may enquire as to the nature of the higher-order structure approaching the MIPS phase boundary [40,41]. Very recently, comparisons have been made between MIPS and criticality in passive systems [41], and in the case of passive systems, approaching criticality, the population of higherorder structure detected by the TCC increases [60], in marked contrast to our findings here. In the future, it would be interesting to investigate whether the trend we have observed changes closer to the MIPS boundary or whether the response of the higher-order structure is profoundly different to passive systems.…”

“…1, we show the state points we consider and the results of our simulations. While other work has addressed the phase diagram of active Brownian particles in two and three dimensions with respect to MIPS [60,61], or reported the full phase diagram of active disks, in which the freezing line is affected by activity [38]; here, we distinguish the crystallisation regimes of nucleation and growth and spinodal by inspection of the crystallinity as a function of time data (see Sect. 3.3).…”

Hunting mermaids in real space: known knowns, known unknowns and unknown unknowns

“…Therefore we conclude that the Asakura-Oosawa model is also well-represented in colloidal systems for particle-resolved studies. It has also been noted that generic short-ranged attractions give similar behaviour [75], which has also be seen in the correspondence of the square-well attraction and colloid-polymer mixtures [76,77].…”

Crystallisation and Polymorph Selection in Active Brownian Particles

“…1, we show the state points we consider and the results of our simulations. While other work has addressed the phase diagram of active Brownian particles in two and three dimensions with respect to MIPS [60,61], or reported the full phase diagram of active disks, in which the freezing line is affected by activity [38]; here we distinguish the crystallisation regimes of nucleation and growth and spinodal by inspection of the crystallinity as a function of time data (see section III C). In particular, we identify behaviour compatible with the passive WCA system for Pe = 0.…”