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Anisotropic and heterogeneous dynamics in an aging colloidal gel
Avni Jain1, Florian Schulz, Irina Lokteva
1Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg, Germany. avni.jain@desy.de.
Soft Matter
|February 29, 2020
Summary
We studied colloidal gel dynamics using X-ray Photon Correlation Spectroscopy (XPCS). We found a nanoscale arrested network and stress-driven relaxation, with dynamics becoming less anisotropic as the gel ages.
Area of Science:
- Soft matter physics
- Colloid science
- Nanoparticle dynamics
Background:
- Colloidal gels exhibit complex out-of-equilibrium dynamics.
- Understanding gelation and aging is crucial for material properties.
Purpose of the Study:
- Investigate the out-of-equilibrium dynamics of colloidal gels near the gelation point.
- Characterize the nanoscale arrested network and its relaxation mechanisms.
- Analyze the anisotropy and aging effects on gel dynamics.
Main Methods:
- X-ray Photon Correlation Spectroscopy (XPCS) was employed.
- Direction-dependent correlation functions were used to assess dynamic anisotropy.
- Higher-order intensity correlations quantified dynamical heterogeneities.
Main Results:
- A dynamically-arrested network at the nanoscale was identified as a gelation signature.
- Slower network dynamics showed hyperdiffusive, compressed exponential behavior, indicative of stress-driven relaxation.
- Anisotropy was greater near the gelation point and decreased with aging.
- Aging significantly influenced intensity correlation fluctuations.
Conclusions:
- The study reveals the structural origins of anisotropic and cooperative heterogeneous dynamics in colloidal gels.
- Results offer insights into stress-driven relaxation and aging phenomena in soft disordered systems.
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