Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Switchable Adhesive: Gel- and polymer-coated surfaces stick together and separate in response to an environmental stimulus

26.07.2007
Two surfaces stick together, separate, and stick together again—on command.

This discovery by a team of researchers from the Universities of Sheffield (UK) and Bayreuth contradicts our day-to-day experience. In the animal kingdom, geckos can climb up vertical inclines, displaying an incredible switchable adhesion as they do so. Insects also use another form of switchable adhesion to sit on your ceiling and then fly off before you climb up on your chair with a rolled-up newspaper. How these animals can switch off and on adhesion is not yet understood in detail. But the scientists led by Mark Geoghegan reveal the secret of their “intelligent” adhesion in the journal Angewandte Chemie.

One of the surfaces involved consists of a polyacid gel, a three-dimensionally cross-linked polymer containing many acid groups. This polymer network is so heavily soaked in liquid that it forms a solid, gelatinous mass. The second surface is a silicon chip onto which a polybase has been deposited. This polybase consists of polymer chains that stretch brush-like from the support and contain many basic groups. In water or slightly acidic solution, the acidic groups carry a positive charge while the basic groups are negatively charged; this causes them to attract each other. In addition to this electrostatic attraction, hydrogen bonds are also formed, which causes the two surfaces to be tightly stuck together.

If the surrounding solution is made more strongly acidic (a pH value of about 1), the bonds break up, the basic groups lose their charge, and the electrostatic attraction lets up. The two surfaces can then be slowly and carefully separated from each other without any damage. This detachment is reversible: If the pH value is raised again, making the solution less acidic, the gel and “brush” stick to each other once again. This cycle can be repeated many times by simply changing the pH value.

Possible applications for such “smart” surface pairs include microelectromagnetic components (actuators), components for microfluidic systems, or carriers for pharmacological agents that could release their cargo under specific physiological conditions.

Jennifer Beal | alfa
Further information:
http://pressroom.angewandte.org

More articles from Ecology, The Environment and Conservation:

nachricht Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>