Lecture

Emulsions: Production and Stabilization

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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 production and stabilization of emulsions, focusing on the properties of colloids, the formation of emulsions through mechanical mixing and sonication, and the different classes of emulsions such as macroemulsions, nanoemulsions, and microemulsions. The instructor explains the role of surfactants and nanoparticles in stabilizing emulsions, the concept of hydrophile-lipophile balance (HLB) to measure surfactant activity, and the types of surfactants including anionic, cationic, and zwitterionic. The lecture also delves into the mechanisms of particle adsorption at liquid-liquid interfaces and the stability of Pickering emulsions.

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 (27)

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).

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).

Adsorption

Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the adsorbate on the surface of the adsorbent. This process differs from absorption, in which a fluid (the absorbate) is dissolved by or permeates a liquid or solid (the absorbent). Adsorption is a surface phenomenon and the adsorbate does not penetrate through the surface and into the bulk of the adsorbent, while absorption involves transfer of the absorbate into the volume of the material, although adsorption does often precede absorption.

Sonication

Sonication is the act of applying sound energy to agitate particles in a sample, for various purposes such as the extraction of multiple compounds from plants, microalgae and seaweeds. Ultrasonic frequencies (> 20 kHz) are usually used, leading to the process also being known as ultrasonication or ultra-sonication. In the laboratory, it is usually applied using an ultrasonic bath or an ultrasonic probe, colloquially known as a sonicator. In a paper machine, an ultrasonic foil can distribute cellulose fibres more uniformly and strengthen the paper.

Colloid

A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend the definition to include substances like aerosols and gels. The term colloidal suspension refers unambiguously to the overall mixture (although a narrower sense of the word suspension is distinguished from colloids by larger particle size).

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