Related Experiment Video
Updated: Jul 12, 2026
08:05
Microtensiometer for Confocal Microscopy Visualization of Dynamic Interfaces
Published on: September 9, 2022
Dynamic interfacial tension at the oil/surfactant-water interface.
Guifeng Li1, Shishir Prasad, Ali Dhinojwala
1Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, USA.
Langmuir : the ACS Journal of Surfaces and Colloids
|August 28, 2007
Summary
Surfactant molecules create an ordered layer at the hexadecane/water interface. This layer may not be crystalline, as interfacial tension changes suggest increased molecular contact and disordering below the interfacial ordering temperature.
Area of Science:
- Physical Chemistry
- Surface Science
Background:
- Surfactant molecules can induce ordered monolayers at liquid-liquid interfaces.
- Understanding interfacial structure is crucial for various chemical and physical processes.
Purpose of the Study:
- To investigate the structure of the ordered monolayer at the hexadecane/water interface using dynamic interfacial tension measurements.
- To determine the nature of the ordered phase and the factors influencing its formation and stability.
Main Methods:
- Dynamic interfacial tension measurements were performed.
- Interfacial tension was monitored during expansion and contraction cycles below the interfacial ordering temperature (Ti).
Main Results:
- No abrupt changes in interfacial tension (gamma) were observed during interfacial cycles below Ti.
- The observed changes in gamma suggest increased water-hexadecane contact and disordering of the interfacial layer, indicating a potentially non-crystalline ordered phase.
- Slower recovery of interfacial tension at low surfactant concentrations suggests a critical concentration is needed for ordered phase nucleation.
Conclusions:
- The ordered phase at the hexadecane/water interface, induced by surfactants, is likely not crystalline.
- The formation of this ordered phase is dependent on a critical surfactant concentration.
- Dynamic interfacial tension measurements provide insights into interfacial layer structure and phase transitions.
More Related Videos
Related Concept Videos
01:24Surface Tension
Surface tension is defined as the force per unit length (γ) acting along the surface of a liquid. It arises due to strong intermolecular forces of attraction. A molecule located inside the bulk of the liquid is surrounded by other molecules and experiences equal forces in all directions. However, a molecule at the surface experiences unbalanced forces because there are more neighboring molecules below than above. This creates a net inward force that pulls surface molecules toward the interior,...
02:57Surface Tension, Capillary Action, and Viscosity
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
01:22Surface Tension of Fluid
Surface tension is a fundamental property of fluids, occurring at the boundary between a liquid and a gas or between two immiscible liquids. This phenomenon arises from the cohesive forces between molecules at the fluid's surface, creating an effect similar to a stretched elastic membrane. Inside each fluid, molecules are equally attracted in all directions by neighboring molecules, but surface molecules experience a net inward force, resulting in surface tension.
Surface tension varies with...
Surface tension varies with...
01:16Surface Tension and Surface Energy
When a paint brush is immersed in water, the bristles wave freely inside the water. When it is taken out, the bristles stick together. The reason behind this effect is surface tension.
Consider a beaker filled with liquid. The bulk molecules in the liquid experience equal attractive forces on all sides with the surrounding molecules. However, the surface molecules experience a net attractive force downward due to the bulk molecules. The surface of the liquid behaves like a stretched membrane,...
Consider a beaker filled with liquid. The bulk molecules in the liquid experience equal attractive forces on all sides with the surrounding molecules. However, the surface molecules experience a net attractive force downward due to the bulk molecules. The surface of the liquid behaves like a stretched membrane,...
01:27Surface Active Agents
Surfactants, named for their behavior at interfaces, positively adsorb at the interfaces of two phases, reducing interfacial tension. Their versatility as emulsifiers, detergents, and foaming agents stems from this ability. Surfactants, often termed amphiphiles, share the property of amphipathy, with molecules having both hydrophilic and hydrophobic portions. The hydrophilic part is called the head, and the hydrophobic part, including an elongated alkyl substituent, forms the tail.Surfactants...
01:13Contact Angle
When a solid is dipped inside a liquid, the liquid surface becomes curved near the contact. For some solid–liquid interfaces, the liquid is pulled up along the solid, while for others, the liquid surface is convex or depressed near the solid surface. This phenomenon can be explained using the concept of cohesive and adhesive forces.
The adhesive force is the molecular force between molecules of different materials, that is, between the molecules of the solid and the liquid. The cohesive force...
The adhesive force is the molecular force between molecules of different materials, that is, between the molecules of the solid and the liquid. The cohesive force...