Lecture

Micelles: Structure and Properties

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In course

MSE-425: Soft matter

The first part of the course is devoted to the self-assembly of molecules. In the second part we discuss basic physical chemical principles of polymers in solutions, at interfaces, and in bulk. Finally, we look at colloids and emulsions. ...

Description

This lecture covers the formation and properties of micelles, focusing on amphiphilic molecules and their role in solubilizing fats in the intestines. It also discusses lyotropic liquid crystals, surface tension in fluids, and the Gibbs adsorption isotherm.

Instructors (2)

Harm-Anton Klok

Expertise Polymer design at nanoscaleBiologically-inspired polymers Mission Research at the Laboratory of Polymer (LP) focuses on the development of novel advanced polymeric materials with potential applications in optics, electronics or medicine. The philosophy is that precise control over nanoscale structure is an important prerequisite to tailor polymer properties. To this end, a “bottom-up” approach is followed, which starts with designing a new material at the molecular level, in order to be able to pr

Esther Amstad

Esther Amstad studied material science at ETH in Zurich. She also carried out her PhD thesis at the same University under the supervision of Prof. Marcus Textor; for her thesis, she worked on the surface modification and steric stabilization of oxide nanoparticles. As a postdoctoral fellow, she joined the experimental condensed soft matter group of David A. Weitz at Harvard University where she used droplet based microfluidics to assemble different types of functional micro- and nanomaterials. In addition, she developped new microfluidic devices that enable the production of very small, airborne drops as well as devices that produce highly monodisperse emulsion drops at a very high throughput. In June 2014, Esther joined the material science department (IMX) of EPFL where she is leading the Soft Materials Laboratory (SMAL).

Official source

Related concepts (18)

Surfactant

Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. Surfactants may function as emulsifiers, wetting agents, detergents, foaming agents, or dispersants. The word "surfactant" is a blend of surface-active agent, coined 1950. Surfactants are usually organic compounds that are akin to amphiphilic, which means that this molecule, being as double-agent, each contains a hydrophilic "water-seeking" group (the head), and a hydrophobic "water-avoiding" group (the tail).

Surface tension

Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to float on a water surface without becoming even partly submerged. At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). There are two primary mechanisms in play.

Micelle

A micelle (maɪˈsɛl) or micella (maɪˈsɛlə) (plural micelles or micellae, respectively) is an aggregate (or supramolecular assembly) of surfactant amphipathic lipid molecules dispersed in a liquid, forming a colloidal suspension (also known as associated colloidal system). A typical micelle in water forms an aggregate with the hydrophilic "head" regions in contact with surrounding solvent, sequestering the hydrophobic single-tail regions in the micelle centre. This phase is caused by the packing behavior of single-tail lipids in a bilayer.

Amphiphile

An amphiphile (from the Greek αμφις amphis, both, and φιλíα philia, love, friendship), or amphipath, is a chemical compound possessing both hydrophilic (water-loving, polar) and lipophilic (fat-loving) properties. Such a compound is called amphiphilic or amphipathic. Amphiphilic compounds include surfactants (these detergents are commonly called "soap" but are different from traditional soap in both composition and method of action for cleaning). The phospholipid amphiphiles are the major structural component of cell membranes.

Emulsion

An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion should be used when both phases, dispersed and continuous, are liquids. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase).

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Suspensions and Emulsions: Phenomenology

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Emulsions: Stabilization Mechanism

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