From DESY: “Scientists synthesise new class of material of a new class”

DESY
DESY

2016/02/01
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Applications in medical technology and manufacturing

Classical materials such as ceramics, metals and polymers have their typical mechanical properties. They are hard, soft, strong, flexible or stiff. Hamburg research scientists have now synthesized a material that unites several different properties, and could thereby open the way to new applications in medical engineering and manufacturing. The scientists from the Hamburg University of Technology (TUHH), the University of Hamburg, the Helmholtz Centre Geesthacht and DESY have presented their novel nanocomposite in the journal Nature Materials. This new class of material could for example be suitable for filling dental cavities, or manufacturing watch cases. The materials used in applications like these need to be both hard and damage-tolerant.

DESY Nanolab I
DESY Nanolab II
DESY Nanolab

The research scientists have developed a new technique which produces a material that is at the same time strong, hard and stiff. To achieve this, the scientists first employed a standard procedure, widely used when working with nanoparticles, whereby ceramic iron oxide nanoparticles are deposited in a regular array. This is done with the help of organic oleic acid, which seeps into the narrow gaps between the nanoparticles and holds them together.

“The self-organisation of these nanoparticles leads to an extended, closely packed supercrystal reminiscent of atomic crystal lattices,” explains one of the authors, Axel Dreyer from the TUHH. The crucial discovery is that by subsequently exposing the material to moderate heat levels, the resulting nanocomposite displays a much stronger cohesion and its mechanical properties are unlike those of any other.

On the smallest scale, the structure of the new material resembles that of biological hard tissues, such as mother of pearl and dental enamel. It consists of uniformly sized iron oxide nanoparticles, which are coated with oleic acid. In previous studies, the bonds between the oleic acid molecules were very weak and due to so-called Van der Waals’ forces. By drying and pressing the material at an elevated temperature and then applying a controlled thermal treatment, the scientist have now managed to create a much stronger bond between the oleic acid molecules, thereby markedly improving the mechanical properties of the nanocomposite.

Since oleic acid is very often used when processing other nanoparticles too, this new method could potentially improve the mechanical properties of a great many other nanocomposites as well. The bonding properties of the oleic acid, which serves as an adhesive, have been examined spectroscopically by the staff of the DESY-Nanolab. “Our measurements showed that the oleic acid molecules survive the thermal treatment and form additional crosslinks during the process,” reports co-author Andreas Stierle, a Leading Scientist at DESY. “This important finding can serve as the basis for successfully modelling the mechanical properties of this novel material.”

Reference:
“Organically linked iron oxide nanoparticle supercrystals with exceptional isotropic mechanical properties“; Axel Dreyer, Artur Feld, Andreas Kornowski, Ezgi D. Yilmaz, Heshmat Noei, Andreas Meyer, Tobias Krekeler, Chengge Jiao, Andreas Stierle, Volker Abetz, Horst Weller and Gerold A. Schneider; „Nature Materials“, 2016; DOI: 10.1038/NMAT4553

See the full article here .

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DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.