Not only rubber is elastic: There is also another, completely different form of elasticity known as superelasticity. This phenomenon results from a change in crystal structure and was previously only found in alloys and certain inorganic materials. A Japanese scientist has now introduced the first superelastic organic compound in the journal Angewandte Chemie.
Superelasticity, also called “pseudoelasticity”, is the ability of special materials that have undergone extensive deformation to return to their original shape when the pressure is released.
This allows some alloys to be stretched out about ten times more than common spring steel without being permanently deformed. The mechanism is different from that involved in the normal elasticity of rubbery substances. In rubber, the polymer chains are stretched out through strain—no compression is possible.
In superelastic materials, mechanical stress triggers a change in the crystal structure—without the individual atoms changing places. When the stress is removed, the materials return to their former structure. Such substances are interesting candidates for use as building materials with “shape memory” in applications such as “self-repairing” vehicle parts.
Superelastic materials other than metal alloys and ceramics have not appeared for over 80 years since the first report of superelasticity in metal alloys. This phenomenon was previously unknown in organic materials. Satoshi Takamizawa of Yokohama City University has now found superelasticity in an organic crystal for the first time: terepthalamide crystals exhibit superelastic behavior with surprisingly little application of force.
Shear stress on a specific surface of the crystal initially causes the crystal to bend, and then transition to a different crystal phase. The more pressure that is applied, the more this spreads throughout the crystal.
When the tension is released, the phase transition moves back across the crystal, which returns to its original structure. Takamizawa and one of his students were able to repeat this superelastic deformation 100 times without any signs of material fatigue.
The crystal consists of individual sheets of slanted terepthalamide molecules (AAAAA sheet arrangement). Shear stress causes the angles of the molecules within the layers to change, which results in a more densely packed A’BA’BA’B sheet arrangement. The layers are held together by a network of hydrogen bridge bonds, which break under pressure and rearrange during the phase transition.
Possible applications of organic superelastic materials include joints made of a single component and elements for dampening vibrations. In medicine, implants made from these types of materials could be deformed for easy introduction and then return to the desired shape and size when they reach the desired location.
About the Author
Dr. Satoshi Takamizawa is Professor of Inorganic Chemistry at Yokohama City University. His main interest is crystal function in coordination compounds and related organic and inorganic materials.
Author: Satoshi Takamizawa, Yokohama City University (Japan), http://nanochem.sci.yokohama-cu.ac.jp/
Title: A Superelastic Crystal of Terephthalamide
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201311014
Dr. Satoshi Takamizawa | Angewandte Chemie
New Model of T Cell Activation
27.05.2016 | Albert-Ludwigs-Universität Freiburg im Breisgau
Fungi – a promising source of chemical diversity
27.05.2016 | Leibniz-Institut für Naturstoff-Forschung und Infektionsbiologie - Hans-Knöll-Institut (HKI)
A biological and energy-efficient process, developed and patented by the University of Innsbruck, converts nitrogen compounds in wastewater treatment facilities into harmless atmospheric nitrogen gas. This innovative technology is now being refined and marketed jointly with the United States’ DC Water and Sewer Authority (DC Water). The largest DEMON®-system in a wastewater treatment plant is currently being built in Washington, DC.
The DEMON®-system was developed and patented by the University of Innsbruck 11 years ago. Today this successful technology has been implemented in about 70...
Permanent magnets are very important for technologies of the future like electromobility and renewable energy, and rare earth elements (REE) are necessary for their manufacture. The Fraunhofer Institute for Mechanics of Materials IWM in Freiburg, Germany, has now succeeded in identifying promising approaches and materials for new permanent magnets through use of an in-house simulation process based on high-throughput screening (HTS). The team was able to improve magnetic properties this way and at the same time replaced REE with elements that are less expensive and readily available. The results were published in the online technical journal “Scientific Reports”.
The starting point for IWM researchers Wolfgang Körner, Georg Krugel, and Christian Elsässer was a neodymium-iron-nitrogen compound based on a type of...
In the Beyond EUV project, the Fraunhofer Institutes for Laser Technology ILT in Aachen and for Applied Optics and Precision Engineering IOF in Jena are developing key technologies for the manufacture of a new generation of microchips using EUV radiation at a wavelength of 6.7 nm. The resulting structures are barely thicker than single atoms, and they make it possible to produce extremely integrated circuits for such items as wearables or mind-controlled prosthetic limbs.
In 1965 Gordon Moore formulated the law that came to be named after him, which states that the complexity of integrated circuits doubles every one to two...
Characterization of high-quality material reveals important details relevant to next generation nanoelectronic devices
Quantum mechanics is the field of physics governing the behavior of things on atomic scales, where things work very differently from our everyday world.
When current comes in discrete packages: Viennese scientists unravel the quantum properties of the carbon material graphene
In 2010 the Nobel Prize in physics was awarded for the discovery of the exceptional material graphene, which consists of a single layer of carbon atoms...
24.05.2016 | Event News
20.05.2016 | Event News
19.05.2016 | Event News
27.05.2016 | Awards Funding
27.05.2016 | Life Sciences
27.05.2016 | Life Sciences