Phase Behavior of Aqueous Suspension of Laponite: New Insights with Microscopic Evidence
arXiv:1704.01737 · doi:10.1021/acs.langmuir.7b00151
Abstract
Investigating microstructure of suspensions with particles having anisotropic shape that share complex interactions is a challenging task leading to competing claims. This work investigates phase behavior of one such system: aqueous Laponite suspension, which is highly contested in the literature, using rheological and microscopic tools. Remarkably, we observe that over a broad range of Laponite (1.4 to 4 weight %) and salt concentrations (0 to 7 mM), the system overwhelmingly demonstrates all the rheological characteristics of the sol-gel transition leading to a percolated network. Analysis of the rheological response leads to fractal dimension that primarily depends on the Laponite concentration. We also obtain the activation energy for gelation, which is observed to decrease with increase in Laponite as well as salt concentration. Significantly, the cryo-TEM images of the post-gel state clearly show presence of a percolated network formed by inter-particle bonds. The present work therefore conclusively establishes the system to be in an attractive gel state resolving a long-standing debate in the literature.
arXiv comment36 pages
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- Aqueous Laponite Dispersions are Attractive Gels, Not Repulsive Wigner Glasses: A Critical Commentary
- Effect of sodium pyrophosphate and understanding microstructure of aqueous LAPONITE(R) dispersion using dissolution study
- Gel-Sol Transition of Thermoresponsive Poly(vinyl alcohol) Solution: Validation of the Universal Critical Scaling Relations
- Evanescent Gels: Competition Between Sticker Dynamics and Single Chain Relaxation
- Salt-induced gelation of nonionic sucrose ester dispersions
- Evolution of Linear Viscoelasticity across the Critical Gelation Transition