The fragile-to-strong dynamical crossover and the system viscoelasticity in attractive glass forming colloids
Journal Article
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· Colloid and Polymer Science
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); CNR-IPCF Messina (Italy); Univ. of Messina (Italy); Office of Scientific and Technical Information (OSTI)
- CNR-IPCF Messina (Italy); Univ. of Messina (Italy)
- Univ. of Messina (Italy)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
The dynamical arrest phenomena of an adhesive hard-sphere (AHS) colloid, L64-D 2O system has been investigated by using calorimetry and the complex shear modulus. This system is characterized by a rich temperature (T) and volume fraction ($$\phi$$) phase diagram with a percolation line (PT). According to the mode-coupling theory (MCT), a cusp-like singularity and two glassy phases, one attractive (AG) and one repulsive (RG), are supposed to coexist in the phase diagram. The MCT scaling laws used to study the shear viscosity with $$\phi$$ and T as control parameters propose the existence of fragile-to-strong dynamic crossover (FSDC) analogous to that observed in molecular supercooled liquid glass formers. The measured critical values of the control parameters, coincident with the PT line, where the clustering process generates the AG phase, define the FSDC locus. This is in agreement with the extended mode-coupling theory that takes into account both cage and inter-cluster hopping effects. Here, we demonstrate, by considering the frequency dependence of the complex moduli, that there is the onset of a system viscoelasticity as an effect of the clustering accompanying the FSDC. We will reveal as the measured frequency-dependent complex moduli satisfy the scaling relations predicted by the scalar elasticity percolation theory and well account for the system evolution toward the glass transition process.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- FG02-90ER45429
- OSTI ID:
- 1557829
- Journal Information:
- Colloid and Polymer Science, Journal Name: Colloid and Polymer Science Journal Issue: 11 Vol. 293; ISSN 0303-402X
- Country of Publication:
- United States
- Language:
- English
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