A new form of self-assembling polymer film that bends and stretches when hit by light is pointing the way to a new family of functional materials. This flexing film is the first material to have been made by coaxing complex molecules to form large-scale, highly ordered three dimensional arrays—a discovery that could change the way that many active material are made, from artificial muscles to solar cells.
Nobuhiko Hosono, Takuzo Aida and colleagues at RIKEN Advanced Science Institute in Wako and The University of Tokyo developed the self-assembly protocol. The researchers found that brush-shaped polymers would form an orderly film when hot-pressed between two sheets of Teflon.
They made their discovery while studying a polymer in which each side chain, or bristle, of the brush structure incorporates light-responsive azobenzenes—two benzene rings separated by a pair of nitrogen atoms. When hit by UV light, the bond between the nitrogens rearranges, contracting the side chain.
The researchers used this photoisomerization behavior to confirm the remarkable long-range order of the polymer structure. Because the side chains were all aligned, when those at the surface were hit by light they curled up in concert, bending the film. A second beam of light at a different wavelength reversed the isomerization process, and the film relaxed back to its original shape.
The trick to making the material is to heat it between two sheets of Teflon that have been drawn tight in one direction, says Hosono. This tension orients the Teflon sheets’ internal structure along a single axis, which acts as a template for the molten polymer brushes sandwiched in between. The side chains of the polymer brush align with the Teflon, pulling each brush upright. As each polymer brush aligns in the same way, it forms a repeating three-dimensional array.
Hosono, Aida and colleagues expect the technique to work for other polymer brushes with similar side chains. To improve the artificial muscle-like behavior of their polymer film, Hosono says the team will try cross-linking the polymer side chains. This will prevent the molecular structure from becoming disordered as the polymer repeatedly curls and relaxes over many cycles, giving the muscle a longer lifetime.
The team is already assessing other potential applications. The wide-area three-dimensional molecular ordering of the polymer brush has great potential for building electronic devices, says Hosono. “We now have designed a new type of polymer brush for development of highly efficient thin-layer organic solar cells.”
The corresponding author for this highlight is based at the Functional Soft Matter Research Group, RIKEN Advanced Science Institute.
 Hosono, N., Kajitani, T., Fukushima, T., Ito, K., Sasaki, S., Takata, M. & Aida T. Large-area three-dimensional molecular ordering of a polymer brush by one-step processing. Science 330, 808-811 (2010).
New design improves performance of flexible wearable electronics
23.06.2017 | North Carolina State University
Plant inspiration could lead to flexible electronics
22.06.2017 | American Chemical Society
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
26.06.2017 | Life Sciences
26.06.2017 | Physics and Astronomy
26.06.2017 | Information Technology