Microgels' behaviour under scrutiny

April 30, 2013

Being a physicist offers many perks. For one, it allows an understanding of the substances ubiquitous in everyday industrial products such as emulsions, gels, granular pastes or foams. These are known for their intermediate behaviour between fluid and solid. Paint, for example, can be picked up on a paintbrush without flowing and spread under the stress of the brush stroke like a fluid. Baudouin Geraud and colleagues from the Light Matter Institute at the University of Lyon, France, have studied the flow of a microgel confined in microchannels. They have shown, in a study just published in the European Physical Journal E, that its behaviour under confinement differs from predictions based on standard theories. Indeed, its molecules are not only subjected to local forces, but also to neighbouring forces that affect its flow.

The authors chose to study the influence of confinement on the flow of a microgel named Carbopol. It is made of jammed polymer blobs, typically a few microns in size, dispersed in water. For the first time, they explored whether this network of polymers can have an impact on the flow of this microgel when confined under a large range of pressure differentials and fluid movement speeds.

They relied on techniques including an approach constraining the complex fluid in sub-millimeter scale microchannels, known as microfluidic. They also used a high-resolution particles' speed called Tracking Particle Velocimetry and studied the flow response to an external force.

Geraud and colleagues confirmed, for the first time in a microgel, that the at a local point do not depend only on the local force but also on the dynamics of its vicinity. This has previously been shown in concentrated emulsions, granular materials and foams under confinement.

Explore further: Unlocking jams in fluid materials: A theoretical model to understand how to best avoid jamming of soft matter

More information: Geraud, B., Bocquet, L. and Barentin, C. (2013), Confined flows of a polymer microgel, European Physical Journal E 36: 30. DOI 10.1140/epje/i2013-13030-3

Related Stories

New theory may shed light on dynamics of large-polymer liquids

August 23, 2011

A new physics-based theory could give researchers a deeper understanding of the unusual, slow dynamics of liquids composed of large polymers. This advance provides a better picture of how polymer molecules respond under fast-flow, ...

Smashing fluids... the physics of flow

November 29, 2010

(PhysOrg.com) -- Hit it hard and it will fracture like a solid... but tilt it slowly and it will flow like a fluid. This is the intriguing property of a type of ‘complex fluid’ which has revealed ‘new physics’ ...

Recommended for you

Electron highway inside crystal

December 8, 2016

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their ...

Researchers improve qubit lifetime for quantum computers

December 8, 2016

An international team of scientists has succeeded in making further improvements to the lifetime of superconducting quantum circuits. An important prerequisite for the realization of high-performance quantum computers is ...

A nano-roundabout for light

December 8, 2016

Just like in normal road traffic, crossings are indispensable in optical signal processing. In order to avoid collisions, a clear traffic rule is required. A new method has now been developed at TU Wien to provide such a ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.