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).
Diamond-like carbon is formed differently to what was believed -- machine learning enables development of new model
19.04.2018 | Aalto University
This 2-D nanosheet expands like a Grow Monster
19.04.2018 | University at Buffalo
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
In an article that appears in the journal “Review of Modern Physics”, researchers at the Laboratory for Attosecond Physics (LAP) assess the current state of the field of ultrafast physics and consider its implications for future technologies.
Physicists can now control light in both time and space with hitherto unimagined precision. This is particularly true for the ability to generate ultrashort...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
19.04.2018 | Materials Sciences
19.04.2018 | Physics and Astronomy
19.04.2018 | Physics and Astronomy