Open Conference Systems, StatPhys 27 Main Conference

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Phase-separating colloidal mixtures: lattice-gas model, composition heterogeneities, and secondary quench
Pablo de Castro, Peter Sollich

##manager.scheduler.building##: Edificio Santa Maria
##manager.scheduler.room##: Auditorio San Agustin
Date: 2019-07-10 12:00 PM – 03:45 PM
Last modified: 2019-06-14

Abstract


We study the dynamics of liquid-gas phase separation in polydisperse fluids by developing theory and simulation based on a lattice-gas model; in particular we test the effects of fractionation, where mixture components are distributed unevenly across coexisting phases. We show that, due to slow fractionation, (i) dense colloidal mixtures phase-separate in two stages and (ii) the denser phase contains long-lived composition heterogeneities, meaning that the actual equilibrium phase compositions may be unobservable in experiments. We develop a two-dimensional histogram method that allows us to analyse slow fractionation effects in any phase-separating mixture. Then, we study the dynamics following a secondary temperature quench. We find a number of interesting effects, mostly associated with the extent to which crowding effects can slow down composition changes. These include long-lived regular arrangements of secondary domains; wetting of fractionated interfaces by oppositely fractionated layers; and filamentous morphologies arising out of secondary domains. In particular, our work could inspire strategies to develop regular morphologies that may have unusual physical properties. More generally, our results could help to further understand the biophysics of membraneless cell organelles.