Related Experiment Video
Updated: Jul 11, 2026
10:56
Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 21, 2014
Osmotic force resisting chain insertion in a colloidal suspension.
M Castelnovo1, R K Bowles, H Reiss
1Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California 90095, USA. castel@chem.ucla.edu
The European Physical Journal. E, Soft Matter
|March 11, 2004
Summary
Inserting a stiff chain into colloidal suspensions requires work due to excluded volume forces. This resistance force, calculated using scaled particle theory and scaling arguments, is significant for biophysical processes.
Area of Science:
- Colloid and Polymer Physics
- Biophysics
Background:
- Colloidal suspensions and polymer solutions are ubiquitous in nature and industry.
- Understanding the interactions between chains and particles is crucial for various applications.
Purpose of the Study:
- To calculate the free energy and force associated with inserting a stiff chain into a colloidal suspension.
- To investigate the role of excluded volume forces in this process.
Main Methods:
- Scaled Particle Theory (SPT) for hard sphere fluids.
- Simple scaling arguments for flexible polymer solutions.
Main Results:
- Calculated the work per unit length as the force resisting chain insertion.
- For nanometer-scale chains and colloids, forces are on the order of tens of pN at moderate volume fractions.
- Demonstrated the applicability of theoretical models to predict these forces.
Conclusions:
- The insertion force is a critical parameter governing chain behavior in colloidal media.
- These forces are relevant to biophysical phenomena, such as DNA ejection from viral capsids.
- The study provides a quantitative basis for understanding chain-colloid interactions.
More Related Videos
Related Concept Videos
03:13Intermolecular Forces
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen bonds, and dispersion...
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...
03:13Intermolecular Forces
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen bonds, and dispersion...
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...
01:09Colloidal 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...
01:29The 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...