Dynamical heterogeneity in a model for permanent gels: Different behavior of dynamical susceptibilities

Abete, T.; Candia, A. de; Gado, Emanuela Del; Fierro, Annalisa; Coniglio, Antonio

doi:10.1103/physreve.78.041404

Cited by 32 publications

(41 citation statements)

References 66 publications

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“…Recent theoretical and simulation studies by Fierro et al [23,32] showed that the dynamics of permanent gels was also non-Gaussian at Fickian time scales and verified systematically that such non-Gaussian dynamics could be understood as a linear combination of the Gaussian displacement distribution functions of different values of D s , where D s is the diffusion coefficient of cluster size s of permanent gels. By employing the percolation theory and assuming the relation between D s and s, they proposed a quantitative theory to explain the complex dynamic behavior of gels in terms of P (D s ) and compared the theory to their simulation results.…”

Section: Introductionmentioning

confidence: 86%

Non-Gaussian rotational diffusion in heterogeneous media

et al. 2014

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We employ a simple model for rotational diffusivity DR of dumbbells in porous media in order to study spatially heterogeneous and non-Gaussian dynamics at Fickian time scales. We obtain the distribution P(DR) of DR's of single dumbbells for both ergodic and nonergodic systems. When a pore percolating network disappears beyond the pore percolation transition and the rotational dynamics becomes nonergodic, each single dumbbell undergoes Gaussian rotational dynamics but with different DR, which depends solely on the local pore structure. We also construct a map of heterogeneous dynamic regions and illustrate that such seemingly Fickian but non-Gaussian dynamics could be understood as the linear combination of the Gaussian rotational displacement distribution functions of each dumbbell. With a percolating pore network, the rotational dynamics becomes ergodic, and P(DR) is a δ function at the average value of DR.

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Section: Introductionmentioning

confidence: 86%

Non-Gaussian rotational diffusion in heterogeneous media

et al. 2014

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“…First, we characterize the cooperative dynamics of the gels by means of the dynamical susceptibility χ 4 . This quantity has been extensively analyzed in numerical simulations of dense glassy systems [31], but it has been relatively less studied in gels [14,15,[32][33][34][35], in spite of the fact that experimental measures of χ 4 in colloidal gels have already been performed [15,32]. We compute χ 4 and its dependence on the scattering wave vector q in networks with varying density, discussing possible connections with experimental observations.…”

Section: Introductionmentioning

confidence: 99%

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

Colombo

Gado

2014

Soft Matter

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We study the assembly into a gel network of colloidal particles, via effective interactions that yield local rigidity and make dilute network structures mechanically stable. The self-assembly process can be described by a Flory-Huggins theory, until a network of chains forms, whose mesh size is on the order of, or smaller than, the persistence length of the chains. The localization of the particles in the network, akin to some extent to caging in dense glasses, is determined by the network topology, and the network restructuring, which takes place via bond breaking and recombination, is characterized by highly cooperative dynamics. We use N V E and N V T Molecular Dynamics as well as Langevin Dynamics and find a qualitatively similar time dependence of time correlations and of the dynamical susceptibility of the restructuring gel. This confirms that the cooperative dynamics emerge from the mesoscale organization of the network.

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“…It is designed to capture the spatiotemporal correlations of particle nobilities and provides, from its peak value, an estimate of the dynamic correlations [50,52]. Such functions have also been analyzed for gels with permanent bonds [53] or low density gels [54].…”

Section: Heterogeneities In Dynamical Propertiesmentioning

confidence: 99%

Relaxation dynamics in a transient network fluid with competing gel and glass phases

Chaudhuri

Hurtado

Berthier

et al. 2015

The Journal of Chemical Physics

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We use computer simulations to study the relaxation dynamics of a model for oil-in-water microemulsion droplets linked with telechelic polymers. This system exhibits both gel and glass phases and we show that the competition between these two arrest mechanisms can result in a complex, three-step decay of the time correlation functions, controlled by two different localization lengthscales. For certain combinations of the parameters, this competition gives rise to an anomalous logarithmic decay of the correlation functions and a subdiffusive particle motion, which can be understood as a simple crossover effect between the two relaxation processes. We establish a simple criterion for this logarithmic decay to be observed. We also find a further logarithmically slow relaxation related to the relaxation of floppy clusters of particles in a crowded environment, in agreement with recent findings in other models for dense chemical gels. Finally, we characterize how the competition of gel and glass arrest mechanisms affects the dynamical heterogeneities and show that for certain combination of parameters these heterogeneities can be unusually large. By measuring the four-point dynamical susceptibility, we probe the cooperativity of the motion and find that with increasing coupling this cooperativity shows a maximum before it decreases again, indicating the change in the nature of the relaxation dynamics. Our results suggest that compressing gels to large densities produces novel arrested phases that have a new and complex dynamics.

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Dynamical heterogeneity in a model for permanent gels: Different behavior of dynamical susceptibilities

Cited by 32 publications

References 66 publications

Non-Gaussian rotational diffusion in heterogeneous media

Non-Gaussian rotational diffusion in heterogeneous media

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

Relaxation dynamics in a transient network fluid with competing gel and glass phases

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