Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Making Colors from Black and White

28.05.2013
It is very annoying when colors fade over time, sometimes simply from exposure to light.

In the journal Angewandte Chemie, Japanese scientists have now introduced a new type of colorfast, environmentally friendly pigment. These consist of submicrometer-sized silicon dioxide particles and carbon black and are simply sprayed on to the desire surface. The resulting color is tough and does not fade.



Organic dyes fade when exposed to UV light. Inorganic pigments do not fade but are often based on toxic heavy metals such as chromium. In contrast, Yukikazu Takeoka, Shinya Yoshioka and their co-workers at the Universities of Nagoya and Osaka have selected silicon dioxide (SiO2), the main component of sand, as the basis for their novel pigments. Submicrometer-sized SiO2 particles look white to the human eye, so where does the color come from?

Conventional pigments absorb some portion of visible light; the reflected portions then combine to produce a certain color. A different type of color generation, known as structural color, is broadly found in nature, for example among butterflies: Arrays of very small particles can also appear colored without absorption by causing wavelength-dependent optical interference, refraction, and light scattering. The color depends of the particle size.

Structural colors are normally iridescent—their color appearance changes depending on the angles of irradiation and observation. This results from the high degree of order of the particles in their crystal lattice. To prevent this, the researchers aimed to avoid crystallization, maintaining their particles in a noncrystalline, amorphous arrangement—a very difficult challenge. The scientists solved this problem by dispersing silicon dioxide nanoparticles in methanol and spraying them onto the surface to be colored.

The methanol evaporates during the spraying process, so the SiO2 lands on the surface as a dry powder, forming a thin, even membrane of amorphous particles; it is given no chance to crystallize. Furthermore, a polyelectrolyte can be used to stabilize the structure of the colloidal amorphous array. Depending on the particle size, the researchers obtained membranes that ranged in color from whitish blue (230 nm) to whitish pink (360 nm).

These amorphous structures only produced very pale colors. However, the team found a solution to this problem: when particles of carbon black were added, the color saturation was significantly increased. The reason for this is that the carbon black particles reduce light scattering over the entire visible spectrum. This new technology thus allows for intensely colored images with many saturated colors as well as Japanese-style paintings in pale colors.

Besides for art objects, the pigments could be used for architectural paints and automotive coatings as well as in cosmetic products.

About the Author
Dr. Yukikazu Takeoka is an Associate Professor at Nagoya University. His research focus on smart materials such as structural colored materials, high mechanical strength gels, densely grafted polymer brushes, and photonic band gap materials for optical and biological applications.

Author: Yukikazu Takeoka, Nagoya University (Japan), mailto:ytakeoka@apchem.nagoya-u.ac.jp

Title: Production of Colored Pigments with Amorphous Arrays of Black and White Colloidal Particles

Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201301321

Yukikazu Takeoka | Angewandte Chemie
Further information:
http://pressroom.angewandte.org

More articles from Life Sciences:

nachricht Scientists enlist engineered protein to battle the MERS virus
22.05.2017 | University of Toronto

nachricht Insight into enzyme's 3-D structure could cut biofuel costs
19.05.2017 | DOE/Los Alamos National Laboratory

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

Im Focus: Hydrogen Bonds Directly Detected for the First Time

For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.

Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

Media accreditation opens for historic year at European Health Forum Gastein

16.05.2017 | Event News

 
Latest News

New approach to revolutionize the production of molecular hydrogen

22.05.2017 | Materials Sciences

Scientists enlist engineered protein to battle the MERS virus

22.05.2017 | Life Sciences

Experts explain origins of topographic relief on Earth, Mars and Titan

22.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>