Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The seashell´s inner beauty

28.05.2003


Scanning electron micrograph of artificial nacre developed by researchers at Oklahoma State University and Digital Instruments/Veeco. One micron is one millionth of a meter.
Credit: Zhiyong Tang, Oklahoma State University; NSF


Photograph depicting artificial nacre and revealing the material’s thin texture and iridescence.
Credit: Zhiyong Tang, Oklahoma State University; NSF


There is more to mother-of-pearl than good looks. Also called nacre, the gleaming, white material is renowned in scientific circles for its strong, yet flexible, properties. Now researchers have developed a nanoscale, layered material that comes close to nacre’s properties, including its iridescence.

The ability to nanomanufacture artificial nacre may provide lightweight, rigid composites for aircraft parts, artificial bone and other applications.

Reporting online in Nature Materials on May 25, Nicholas Kotov and his colleagues at Oklahoma State University and at Digital Instruments/Veeco describe their method for creating nacre-like material that consists of alternating layers of clay and a type of polymer called a polyelectrolyte. Kotov received a National Science Foundation (NSF) CAREER Award to pursue the work.



"The discovery allows researchers to tailor flexible materials to a given application-to get the tough materials that nature has been able to produce," said Lynn Schneemeyer, the NSF program officer who oversees Kotov’s award. NSF is an independent federal agency that supports fundamental research and education across all fields of science and engineering.

Natural nacre owes much of its strength and flexibility to an internal brick-like structure. Protein layers only nanometers (billionths of a meter) thick provide the pliable "mortar," while calcium carbonate, the principal chemical in limestone and antacids, comprises the similarly miniscule "bricks" adding hardness.

In the artificial nacre, platelets of a negatively-charged clay called montmorillonite provide the bricks while fibers of a positively-charged polyelectrolyte called poly(diallydimethylammonium) chloride (PDDA) serve as the mortar. The opposite charges help the two components bond tightly to form the nacre structure.

"The combination of montmorillonite and PDDA for nacre modeling came to us quite naturally," said Kotov. "It was the very first clay-polyelectrolyte system I worked with a few years back." He also states that the montmorillonite has several advantages over other layered minerals, such as talc, including an ability to disperse easily in water, while the PDDA has a high affinity for clays.

Unique "sacrificial bonds" hold the polymer chains to each other in a special way that maintains strength and flexibility. The bond is a result of the polymer interacting with negative charges on the clay surfaces (or, in the case of real nacre, proteins interacting with positive calcium ions).

Such ionic bonds are strong and absorb energy when the artificial nacre is deformed. If the bonds break, they can reform when the stress goes away. They are dubbed "sacrificial" because they take the brunt of an attack, leaving the covalent bonds in the molecules intact.

The artificial nacre was created by immersing a glass slide in alternating baths of clay and polymer. A robotic device performed the 200 dips, with each dip producing several plastic clay layers-each clay and plastic layer is, on average, only 24 nanometers thick.

"It is a very robust preparation and produces beautiful layers every time," said Kotov.

Because of the artificial nacre’s potential for highstrength, protective coatings such as body armor and biocompatible substrates for growing human tissue or organs, Kotov and his colleagues are working with a company to further develop the material and techniques. And, because researchers can easily add new components like ultraviolet light- or corrosion resistant chemicals to the artificial nacre, the same manufacturing process can produce materials for a variety of applications.

Josh Chamot | NSF
Further information:
http://www.nsf.gov
http://www.nsf.gov/od/lpa/news/media/start.htm
http://www.nsf.gov/od/lpa

More articles from Materials Sciences:

nachricht Nanomaterial makes laser light more applicable
28.03.2017 | Christian-Albrechts-Universität zu Kiel

nachricht New value added to the ICSD (Inorganic Crystal Structure Database)
27.03.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Periodic ventilation keeps more pollen out than tilted-open windows

29.03.2017 | Health and Medicine

Researchers discover dust plays prominent role in nutrients of mountain forest ecoystems

29.03.2017 | Earth Sciences

OLED production facility from a single source

29.03.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>