Non-diffusive dynamics in a colloidal glass: Aging versus rejuvenation

Angelini, Roberta; Ruzicka, Barbara

doi:10.1016/j.colsurfa.2015.06.001

Cited by 13 publications

(12 citation statements)

References 40 publications

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“…(6). It evolves from an exponential behaviour τ = τ 0 exp( D t t w t ∞ w −t w ) (3,5,6,9) where t w drives the system out of equilibrium and t ∞ w sets the apparent divergence (56,57), to a slower than Arrhenius dependence with increasing t w . Fig.…”

Section: Resultsmentioning

confidence: 99%

Relaxation Dynamics, Softness, and Fragility of Microgels with Interpenetrated Polymer Networks

et al. 2020

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Microgels are elastic and deformable particles with a hybrid nature between that of polymers and colloids and unconventional behaviours with respect to hard colloids. We investigated the dynamics of a soft microgel made of interpenetrated polymer networks of PNIPAM and PAAc by means of coherent X-ray and light scattering techniques. By varying the particle softness through PAAc content we can tune at wish the fragility of IPN microgels. Interestingly we find the occurrence of a dynamical crossover at a critical packing fraction which leads to an evolution of the structural relaxation time from super-Arrhenius to Ar-1 rhenius, a minimum for the shape of the intensity autocorrelation function and the emerging of distinct anomalous mechanisms for particle motion. This complex phenomenology can be modelled by a Fickian diffusion at very low concentrations, an effective non Fickian anomalous diffusion at intermediate values and a ballistic motion well described within the Mode Coupling Theory on approaching the glassy state.

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Section: Resultsmentioning

confidence: 99%

Relaxation Dynamics, Softness, and Fragility of Microgels with Interpenetrated Polymer Networks

et al. 2020

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“…[8]. It changes from a VFT behaviour τ = τ 0 exp( D t t w t ∞ w −t w ) [5,7,8,12] where t w replaces 1/T and t ∞ w sets the apparent divergence [66,67], to a slower than Arrhenius behaviour with increasing t w . Moreover in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…the slowing down of the dynamics achieved by varying packing fraction [47,69], waiting time [5,7,8,12] or temperature [22,23] is accompanied by a super Arrhenius increase, typically VFT, of the structural relaxation time followed by a slower than Arrhenius or an Arrhenius behaviour. Thus the existence of two different dynamical regimes is a general feature of soft colloids, hard colloids and structural glasses.…”

Section: Resultsmentioning

confidence: 99%

“…where τ is an "effective" relaxation time and β measures the distribution of relaxation times (associated with simple exponential decays) and assumes generally positive values β <1 (stretched behaviour). However recently an anomalous dynamics, characterized by a shape parameter β >1 (compressed behaviour), has emerged in out of equilibrium states of different materials like colloidal glasses [5][6][7][8][9][10][11][12][13], gels [14][15][16][17][18][19], supercooled liquids [20,21], metallic glasses [22,23], polymeric systems [24][25][26], ceramics [27] and investigated also in theoretical [28][29][30][31] and simulation [32][33][34][35] works. The existence of stretched and/or compressed correlation functions is currently a very debated issue also faced in this work.…”

Section: Introductionmentioning

confidence: 99%

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Structural relaxation, softness and fragility of IPN Microgels

Nigro¹,

Ruzicka²,

Ruta³

et al. 2018

Preprint

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“…Each of these factors can affect the interparticle interactions and consequently the viscoelastic properties. For instance, the presence of charged species has been shown to alter the liquid to gel transition in laponite suspensions [32][33][34]. Suspensions and gels of cellulose nanocrystals are a compelling case in point, as they display a wide variety of solvent-mediated interparticle interactions including van der Waals attraction, hydrogen bonding and electrostatic repulsion [35,36].…”

Section: Introductionmentioning

confidence: 99%

Shear melting and recovery of crosslinkable cellulose nanocrystal–polymer gels

et al. 2019

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Cellulose nanocrystals (CNC) are naturally-derived nanostructures of growing importance for the production of composites having attractive mechanical properties, and offer improved sustainability over purely petroleum-based alternatives. Fabrication of CNC composites typically involves extrusion of CNC suspensions and gels in a variety of solvents, in the presence of additives such as polymers and curing agents. However, most studies so far have focused on aqueous CNC gels, yet the behavior of CNC-polymer gels in organic solvents is important to their wider processability. Here, we study the rheological behavior of composite polymer-CNC gels in dimethylformamide, which include additives for both UV and thermal crosslinking. Using rheometry coupled with in-situ infrared spectroscopy, we show that under external shear, CNC-polymer gels display progressive and irreversible failure of the hydrogen bond network that is responsible for their pronounced elastic properties. In the absence of cross-linking additives, the polymer-CNC gels show negligible recovery upon cessation of flow, while the presence of additives allows the gels to recover via van der Waals interactions. By exploring a broad range of shear history and CNC concentrations, we construct master curves for the temporal evolution of the viscoelastic properties of the polymer-CNC gels, illustrating universality of the observed dynamics with respect to gel composition and flow conditions. We therefore find that polymer-CNC composite gels display a number of the distinctive features of colloidal glasses and, strikingly, that their response to the flow conditions encountered during processing can be tuned by chemical additives. These findings have implications for processing of dense CNC-polymer composites in solvent casting, 3D printing, and other manufacturing techniques. arXiv:1901.04373v1 [cond-mat.soft]

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Non-diffusive dynamics in a colloidal glass: Aging versus rejuvenation

Cited by 13 publications

References 40 publications

Relaxation Dynamics, Softness, and Fragility of Microgels with Interpenetrated Polymer Networks

Relaxation Dynamics, Softness, and Fragility of Microgels with Interpenetrated Polymer Networks

Structural relaxation, softness and fragility of IPN Microgels

Shear melting and recovery of crosslinkable cellulose nanocrystal–polymer gels

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