Influence of the Glass Transition on the Liquid-Gas Spinodal Decomposition

Abstract

We use large-scale molecular dynamics simulations to study the kinetics of the liquid-gas phase separation if the temperature is lowered across the glass transition of the dense phase. We observe a gradual change from phase separated systems at high temperatures to nonequilibrium, gel-like structures that evolve very slowly at low temperatures. The microscopic mechanisms responsible for the coarsening strongly depend on temperature, and change from diffusive motion at high temperature to a strongly intermittent, heterogeneous and thermally activated dynamics at low temperature, leading to logarithmically slow growth of the typical domain size.

Ultra-long-range dynamic correlations in a microscopic model for aging gels

“…A more recent work on a low density gel reported instead subdiffusive behaviour [37]. At a more coarse-grained level, it was suggested that localised bondbreaking events in gels may result in compressed exponentials [38], a mean-field scenario that was recently revisited using a mesoscopic elasto-plastic model for generic glassy materials [39], in which the gel structure however plays no direct role.Using large-scale numerical simulations of a particlebased model for gel formation [13,14], we show that the spontaneous microscopic aging dynamics during gelation possesses all anomalous signatures reported experimentally. We find a subdiffusive aging dynamics at short lengthscales, corresponding to caged particle motion inside the gel strands, crossing over to superdiffusive relaxation at larger lengthscales triggered by intermittent snapping of the fractal network.…”

“…Using large-scale numerical simulations of a particlebased model for gel formation [13,14], we show that the spontaneous microscopic aging dynamics during gelation possesses all anomalous signatures reported experimentally. We find a subdiffusive aging dynamics at short lengthscales, corresponding to caged particle motion inside the gel strands, crossing over to superdiffusive relaxation at larger lengthscales triggered by intermittent snapping of the fractal network.…”

“…A prevalent method to form physical gels follows a nonequilibrium route by quenching a homogeneous fluid into a phase coexistence region [1,[7][8][9][10][11][12], which generates bicontinuous structures. When the dense phase forms an amorphous solid, the phase separation is kinetically hindered [13][14][15][16] and a gel forms. The microscopic dynamical and structural properties of these nonequilibrium gels evolve slowly with time.…”

“…Following previous work [13,14], we study the properties of a binary Lennard-Jones mixture after it is suddenly quenched into its liquid-gas phase coexistence region. To access large-enough system sizes, we work in two spatial dimensions.…”

Self-assembly and cooperative dynamics of a model colloidal gel network

“…In recent years a number of approaches for simulating colloidal gelation have been proposed, including shortrange isotropic interactions [21][22][23][24], valence-limited and patchy-particle models [25][26][27], dipolar particles [28], and anisotropic effective interactions [18,29,30]. We follow here this latter approach, using an effective interaction that includes, in the form of a three-body term, the basic ingredients for a minimal model of particle gels.…”