Microstructure, microrheology, and dynamics of laponite® and laponite®-poly(ethylene oxide) glasses and dispersions
| Autor: | James R. Breton, Surita R. Bhatia, Bingqian Zheng, Ruchi S. Patel |
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| Rok vydání: | 2020 |
| Předmět: |
Microrheology
Gel point Materials science 010304 chemical physics Oxide Condensed Matter Physics Microstructure 01 natural sciences Viscoelasticity 010305 fluids & plasmas chemistry.chemical_compound Chemical engineering Dynamic light scattering chemistry Rheology 0103 physical sciences General Materials Science Microscale chemistry |
| Zdroj: | Rheologica Acta. 59:387-397 |
| ISSN: | 1435-1528 0035-4511 |
| Popis: | We utilize dynamic light scattering (DLS)-based passive microrheology to probe the dynamics and structural evolution of laponite® and laponite®-polymer glasses and dispersions at the microscale. The results reveal an increase in the dynamic heterogeneity of laponite® dispersions with an increase of laponite® concentration and aging time. In neat laponite® dispersions, the degree of stiffness is enhanced and the dynamics are retarded at higher laponite® concentration due to the formation of a repulsive glass. In the presence of PEO with a moderate molecular weight of 20 kg/mol, the microviscoelastic properties of 2 wt% laponite® dispersions show non-monotonic effects with PEO concentration upon aging, which agrees with the results obtained previously from bulk rheology. However, the magnitudes of the viscoelastic moduli (G’ and G”) of dispersions beyond the gel point obtained from DLS-microrheology is lower than that obtained from conventional rheology. Our results suggest that the DLS-microrheology can be used to qualitatively study dynamic transitions and the microviscoelastic properties of gels and soft solids. |
| Databáze: | OpenAIRE |
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