Related Experiment Video
Updated: Jun 25, 2026
10:56
Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
Dynamic properties of confined hydration layers
Susan Perkin1, Ronit Goldberg, Liraz Chai
1Department of Physical and Theoretical Chemistry, University of Oxford, Oxford, UK.
Faraday Discussions
|February 21, 2009
Summary
Aqueous salt solutions confined to thin films exhibit varied behaviors. Hydration lubrication depends on ion type, with Na+ and Cs+ showing distinct responses under pressure and confinement.
Area of Science:
- Physical Chemistry
- Surface Science
- Nanotechnology
Background:
- Water and Na+ solutions are fluid-like in thin films between mica surfaces.
- Previous studies explored confined fluid behavior.
Purpose of the Study:
- Compare shear and normal forces of Na+, Cs+, and Ni2+ salt solutions under confinement.
- Investigate the 'hydration lubrication' mechanism by examining ion properties.
Main Methods:
- Confined film studies using mica surfaces.
- Measurement of shear and normal forces.
- Comparison of 0.1 M Na+, Cs+, and Ni2+ solutions.
Main Results:
- Hydrated Na+ films remain fluid up to 10 atm.
- Cs+ films lack hydration repulsion due to lower hydration energy.
- Ni2+ solutions maintain bulk viscosity in thin films but show no hydration repulsion.
Conclusions:
- Ion type significantly influences confined fluid behavior and lubrication.
- Hydration energy and valency are key factors in 'hydration lubrication'.
Related Concept Videos
02:42Aqueous Solutions and Heats of Hydration
Water and other polar molecules are attracted to ions. The electrostatic attraction between an ion and a molecule with a dipole is called an ion-dipole attraction. These attractions play an important role in the dissolution of ionic compounds in water.
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
01:24Hydration of Cement
Hydration of cement is a chemical reaction between cement particles and water. This process occurs primarily through two mechanisms: through-solution and topochemical. In the through-solution process, anhydrous compounds dissolve into their constituents, hydrates form in the solution, and then precipitate from the supersaturated solution. The topochemical process involves solid-state reactions at the cement particle surface. The through-solution process dominates the topochemical process at the...
01:29Strength and Heat of Hydration
The hydration of cement is an exothermic reaction in which heat is generated as cement hydrates. This heat of hydration is critical to cement's strength development. The rate at which this heat is generated affects the temperature rise, with a majority of the heat being released early in the hydration process, half within the first three days, and about 75% within the first week.
The heat of hydration for each cement compound is significant; for instance, tricalcium aluminate (C3A) and...
The heat of hydration for each cement compound is significant; for instance, tricalcium aluminate (C3A) and...
01:28Transition Zone
The transition zone in concrete is a critical area where aggregate meets cement paste, marked by a distinct porosity and weakness compared to the surrounding material. The adhesion around the aggregates is primarily due to Van Der Waals forces. The voids within this zone influence its robustness; initially, it is less durable than the surrounding bulk mortar due to larger voids. Initially, when concrete is compacted, a higher water-cement ratio near the aggregates leads to the formation of...
01:30The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...
01:12Total Voids in Concrete
Total voids in concrete encompass gel water volume, capillary pores, and entrapped air. Gel water (retained within the cement hydration products) and physically entrapped or adsorbed water are significant for the hydration process. For complete hydration, it's estimated that the space needed for the products of a cubic centimeter of cement doubles. Capillary pores constitute the unoccupied space within the hydrated cement paste, with their size largely influenced by the water-to-cement ratio...