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

Colombo, Jader; Gado, Emanuela Del

doi:10.1039/c4sm00219a

Cited by 50 publications

(62 citation statements)

References 62 publications

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“…where r is the interparticle distance rescaled by the particle diameter and A and a are dimensionless constants. In particular we have fixed A = 6.27, a = 0.85 to obtain a short-ranged attractive well of depth and range 0.3σ [50,51]. We adopt periodic boundary conditions and, using the particle diameter σ, we define an approximate volume (surface) fraction φ g = π(σ/2) 2 N/L 2 , where L is the side length of the square simulation box (in units of σ).…”

Section: Appendix B: Colloidal Gel Simulationmentioning

confidence: 99%

Correlated Rigidity Percolation and Colloidal Gels

Zhang

Bouzid

et al. 2019

Phys. Rev. Lett.

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Rigidity percolation (RP) occurs when mechanical stability emerges in disordered networks as constraints or components are added. Here we discuss RP with structural correlations, an effect ignored in classical theories albeit relevant to many liquid-to-amorphous-solid transitions, such as colloidal gelation, which are due to attractive interactions and aggregation. Using a lattice model, we show that structural correlations shift RP to lower volume fractions. Through molecular dynamics simulations, we show that increasing attraction in colloidal gelation increases structural correlation and thus lowers the RP transition, agreeing with experiments. Hence colloidal gelation can be understood as a RP transition, but occurs at volume fractions far below values predicted by the classical RP, due to attractive interactions which induce structural correlation. arXiv:1807.08858v1 [cond-mat.soft]

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Section: Appendix B: Colloidal Gel Simulationmentioning

confidence: 99%

Correlated Rigidity Percolation and Colloidal Gels

Zhang

Bouzid

et al. 2019

Phys. Rev. Lett.

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“…In spite of its simplicity, our model captures important physical features of real colloidal gels and can be used as a prototypical soft amorphous solid. Starting from this elementary information, we have used anisotropic interactions to introduce local rigidity and stabilize selfassembled thin open structures at low volume fraction [27,33], in the same spirit as recent works [34,35]. Our system consists of N identical particles with position vectors {r i } , i = 1 .…”

Section: Model and Numerical Simulationsmentioning

confidence: 99%

“…The potential energy (1) depends parametrically on the dimensionless quantities A, a, B,θ, w. We have chosen these parameters such that for k B T ∼ 10 −1 the particles start to self-assemble into a persistent particle network. The data here discussed refer to A = 6.27, a = 0.85, B = 67.27,θ = 65 • , w = 0.30, one convenient choice to realize this condition.This model has been used to perform a spatially resolved analysis of cooperative dynamics in colloidal gel networks, of their aging and mechanical response [20,21,27,33]. The network structure is characterized by the cohexistence of poorly connected regions, where major structural rearrangements take place and densely connected domains, where internal stresses tend to concentrate.…”

Section: Model and Numerical Simulationsmentioning

confidence: 99%

Network Topology in Soft Gels: Hardening and Softening Materials

Bouzid

Gado

2017

Langmuir

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The structural complexity of soft gels is at the origin of a versatile mechanical response that allows for large deformation, controlled elastic recovery, and toughness in the same material. A limit to exploiting the potential of such materials is the insufficient fundamental understanding of the microstructural origin of the bulk mechanical properties. Here we investigate the role of the network topology in a model gel through 3D numerical simulations. Our study links the topology of the network organization in space to its nonlinear rheological response preceding yielding and damage: our analysis elucidates how the network connectivity alone could be used to modify the gel mechanics at large strains, from strain-softening to hardening and even to a brittle response. These findings provide new insight for smart material design and for understanding the nontrivial mechanical response of a potentially wide range of technologically relevant materials.

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

Cited by 50 publications

References 62 publications

Correlated Rigidity Percolation and Colloidal Gels

Correlated Rigidity Percolation and Colloidal Gels

Network Topology in Soft Gels: Hardening and Softening Materials

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

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