Related Experiment Video
Updated: Jun 27, 2026
10:56
Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 20, 2014
Gravitational compression of colloidal gels.
J J Liétor-Santos1, C Kim, P J Lu
1Department of Physics and HSEAS, Harvard University, Pierce Hall, 29 Oxford Street, Cambridge, MA 02138, USA.
The European Physical Journal. E, Soft Matter
|November 20, 2008
Summary
Depletion gels compress unevenly, developing a volume fraction gradient under gravitational stress. A non-linear poroelastic model accurately describes this phenomenon, accounting for stress dependencies.
Area of Science:
- Soft Matter Physics
- Materials Science
Background:
- Depletion gels are complex fluids exhibiting unique mechanical properties.
- Understanding their behavior under stress is crucial for material design and application.
Purpose of the Study:
- To investigate the compression behavior of depletion gels under gravitational stress.
- To analyze the evolution of the gel interface and local volume fraction during compression.
Main Methods:
- Monitoring the time evolution of the gel interface.
- Measuring the local volume fraction (φ) within the gel.
- Utilizing a non-linear poroelastic model for analysis.
Main Results:
- The volume fraction (φ) is not uniform within the gel during compression.
- A significant volume fraction gradient develops and increases with gel height.
- The observed behavior is accurately predicted by the poroelastic model.
Conclusions:
- Gravitational stress induces non-uniform compression in depletion gels.
- The developed volume fraction gradient is a key feature of gel compression.
- The non-linear poroelastic model provides a robust framework for describing these complex stresses.
More Related Videos
13:30A Novel Method for Localizing Reporter Fluorescent Beads Near the Cell Culture Surface for Traction Force Microscopy
Published on: September 16, 2014
11:38Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions
Published on: April 19, 2018
Related Concept Videos
03:22Colloids
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles that are visible to the naked eye or can be seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. On the other hand, a solution is a homogeneous mixture in which no settling occurs and in which the dissolved...
01:29The Colloidal State
The formation of a colloidal system is exemplified by an aqueous solution containing Cl− ions is introduced to another containing Ag+ ions, resulting in the precipitation of solid AgCl as extremely tiny crystals. Instead of settling out as a filterable precipitate, these crystals remain suspended in the liquid, showcasing a colloidal system.A colloidal system involves colloidal particles within the approximate range of 1 to 1000 nm in at least one dimension, dispersed in a medium called the...
01:09Colloidal precipitates
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
01:17Colloids and Suspensions
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles visible to the naked eye or seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. The suspended particles in a suspension settle out after some time of mixing. The separation of particles from a suspension is...
01:06Coagulation
Colloidal solids are solid particles suspended in solution. They are usually negatively charged, attracting a compact primary layer of positively charged ions, which attract more counterions to form an electrical double layer. Electrostatic repulsion between the charged double layers prevents the particles from colliding, stabilizing the colloids. These solids are often undesirable because they can contain toxins that are difficult to remove. Coagulation is a technique that helps aggregate and...
01:22Problem Solving on Stress and Strain
Stress is a quantity that describes the magnitude of a force that causes deformation, generally defined as internal force per unit area. When forces pull on an object and cause its elongation, like the stretching of an elastic band, it is called tensile stress. When forces cause the compression of an object, it is known as compressive stress. When an object is being squeezed uniformly from all sides, like a submarine in the depths of the ocean, we call this kind of stress bulk stress (or volume...