AI Article Synopsis
- Sodium-montmorillonite (Na-Mt) particles have a surface charge that varies with pH, suggesting that adjusting pH can influence how these particles interact in suspension and affect their dynamics.
- Rheological experiments indicated that Na-Mt suspensions exhibited stronger physical aging and elastic response in acidic conditions (pH < 9.5) compared to basic conditions (pH ≥ 9.5).
- Findings showed that as pH changes impact particle interactions, there was a notable difference in the behavior of the suspension's yield stress and viscosity, supporting the idea that lower pH creates a more stable microstructure among particles.
Article Abstract
Hypothesis: Sodium-montmorillonite (Na-Mt) particles are geometrically anisometric that carry a pH dependent anisotropic surface charge. Therefore, it should be possible to manipulate the particle-particle interaction of colloidal range Na-Mt suspensions through pH changes which in turn should alter the soft glassy dynamics of Na-Mt suspensions.
Experiments: Rheological experiments were used to probe the impact of pH mediated colloidal particle-particle interaction on the physical aging, linear viscoelastic response, and yield stress behavior of Na-Mt suspension.
Findings: The temporal evolution of the storage modulus (G') was stronger in the acid regime (pH < 9.5) than the base (pH ≥ 9.5) pH regime. Horizontal shifting of the aging curves in the acid and base regimes led to aging time-H concentration and aging time-OH concentration superposition. An aging time-Na-Mt concentration superposition was also observed in both pH regimes. The critical stress associated with the viscosity bifurcation behavior increased linearly with G' but with different slopes for acid and base regime. We propose that positively charged patches on the Na-Mt particle edge merge with the characteristic surface as a function of H ions in the system. This leads to a strongly associated microstructure at low pH and a relatively weak but associated microstructure at natural pH, hence confirming the hypothesis.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.jcis.2021.08.034 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
The structure-dynamics feedback mechanism governs the glassy dynamics in epithelial monolayers.
Soft Matter
January 2025
Tata Institute of Fundamental Research, Gopanpally Village, Hyderabad-500046, India.
The glass-like slow dynamics in confluent epithelial monolayers is crucial for wound healing, embryogenesis, cancer progression, Experiments have indicated several unusual properties in these systems. Unlike ordinary glasses, the glassiness in cellular systems strongly correlates with their static properties and is sub-Arrhenius. These results imply that the slow dynamics in epithelial monolayers is either not glassy or the underlying mechanism is different from ordinary glasses.
View Article and Find Full Text PDFRubbery organic frameworks (ROFs) toward ultrapermeable CO-selective membranes.
Sci Adv
November 2024
Institut Européen des Membranes, Adaptive Supramolecular, Nanosystems Group, University of Montpellier, ENSCM, CNRS, Place Eugène Bataillon, CC 047, F-34095, Montpellier, France.
The capture of CO is of high interest in our society representing an essential tool to mitigate man-made climate warming. Membrane technology applied for CO capture offers several advantages in terms of energy savings, simple operation, and easy scale-up. Glassy membranes are associated with low gas permeability that negatively affect on their industrial implementation.
View Article and Find Full Text PDFAlginate/Chitosan Complex Fibers Reinforcement and Their Mechanical Transition Continuum With Water Uptake Increasing.
Macromol Rapid Commun
November 2024
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Center for Advanced Low-Dimension Materials, College of Materials Science and Engineering, Donghua University, Shanghai, 201620, P. R. China.
Living tissues span a remarkable spectrum of modulus ranging from the level of Pa to GPa in a water-rich environment. Constructing soft and hard materials that match the mechanics of tissues and researching mechanical transition in water, are beneficial for their biological applications. Here, using polyelectrolyte complex fiber as a model system and reinforcing the fiber by stepwisely introducing additional coordination and covalent bonds, this investigated that the water effect on mechanical transition behaviors.
View Article and Find Full Text PDFPhysically crosslinked polyacrylates by quadruple hydrogen bonding side chains.
J Mater Chem B
December 2024
Supramolecular Chemistry Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, B-9000 Ghent, Belgium.
Dynamic polymer materials can be obtained by introducing supramolecular interactions between the polymer chains. Here we report on the preparation and mechanical properties of poly(methyl acrylate) (PMA) and poly(-butyl acrylate) (PBA) funcionalized with ureidopyrimidinone (UPy) in the side chains. In contrast to the traditional UPy with a methyl group, the selected UPy motif contained a branched alkyl side chain, which enhances solubility, compatibility with the polymer matrix and potentially prevents stacking of UPy dimers.
View Article and Find Full Text PDFPickering emulsions for stimuli-responsive transdermal drug delivery: effect of rheology and microstructure on performance.
Soft Matter
November 2024
Department of Chemical Engineering, University College London, London, UK.
This work investigates the design of stimuli-responsive Pickering emulsions (PEs) for transdermal drug delivery applications, by exploring the impact of stabilising microgels size and interactions on their rheological and release properties. Temperature-responsive poly(-isopropylacrylamide) microgels modified with 1-benzyl-3-vinylimidazolium bromide (pNIPAM--BVI) are synthesized in varying sizes and used to stabilise jojoba oil-in-water concentrated emulsions. The results reveals two distinct behaviours: for small microgels (∼300 nm), the PEs exhibit a smooth, uniform structure characterised by a mild yield stress, characteristic of soft glassy systems.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!