Discussant: Srikanth Sastry JNCASR, Bangalore, India
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Transcript of Discussant: Srikanth Sastry JNCASR, Bangalore, India
Discussant: Srikanth SastryJNCASR, Bangalore, India
Dynamical heterogeneities in Chemical gels Dynamical heterogeneities in Chemical gels and attractive colloidsand attractive colloids
Antonio ConiglioAntonio Coniglio
• Summary of main points in Antonio’s talk.
• What is new and interesting.
• Discussion of these in the context of glass formers and gel formers.
OutlineOutline
Systems of interest: Chemical and colloidal gels
Model systems: i. LJ + FENE bonds (chemical gel),
ii. DLVO (colloidal gel)
Phenomenon: Dynamical heterogeneity
Chemical gels: • in the limit of large time mean cluster size of
percolation. • k dependence of yields percolation exponents.
Colloids: • given by the mean cluster size of mobile
particles. • Differences in the behavior of depending on
definition (Fs(k,t) vs. overlap Q).
Summary of resultsSummary of results
• The asymptotic (t -> infinity, k -> 0) value of gives the mean size of percolation clusters.
as(k) gives additional information about the structure of percolation clusters.
• In this case, dynamical heterogeneity is understood from geometry.
• Looking at dynamical heterogeneity offers a way of obtaining geometric information.
•
What is new and interesting: Connection between What is new and interesting: Connection between dynamical heterogeneity and percolation dynamical heterogeneity and percolation
• Is dynamical heterogeneity that arises from structural heterogeneity interesting?
• In “attractive glasses”, gels etc, aspects of bonding and connectivity play a definite role, so has to be taken into account.
• Are there circumstances where looking at
dynamical heterogeneity would be a relevant approach to getting information on structure?
• ?
What is new and interesting: Connection between What is new and interesting: Connection between dynamical heterogeneity and percolation: Questions dynamical heterogeneity and percolation: Questions
• Description of dynamics in terms of the size dependent mobility of clusters.
• Useful in the case of transient clusters?
What is new and interesting: Describing dynamics What is new and interesting: Describing dynamics
• Qualitative dependence of dynamical susceptibility on definition via Fs(k,t) or overlap Q(t;a).
• Unlikely to affect results in high density glassy systems but a caution to heed.
What is new and interesting: Matters of What is new and interesting: Matters of definitiondefinition
• For transient bonds, dynamical susceptibility related to mean cluster size of mobile particles.
• At high densities, “excess” heterogeneity indicative of crossover in dynamics?
• But mean cluster size captures peak value in both cases.
• ?• It will be interesting to study this
relation in gel other models, with tunable bond life times ec (Hurtado, Chaudhuri, Berthier, Kob; Saw, Kob, Sastry; Del Gado, Kob)
What is new and interesting: Transient bonds What is new and interesting: Transient bonds