Powder from scrap tires can bring color to displays

Physicists have discovered how to transform recovered carbon black powder to offer a wide range of colors for potential display applications.

Recovered carbon black powder is a common pigment produced from scrap rubber tires. There is a growing demand to use it as an environmentally friendly and sustainable material as a reinforcing filler in tires and many other applications.

Applying focused laser treatment to recovered carbon black powder through a photo-thermal process can make it display a wide range of colors, the researchers found.

black carbon blue butterfly
Figure shows a multicolor butterfly design which is made by patterning recovered carbon black in ambient and helium environments. (Credit: NUS)

Recovered carbon black powder often contains different types of metal impurities, a flaw that many deem undesirable. However, when researchers heated it in air or in a helium environment using a focused laser beam, the carbon atoms get infused into the metal contaminates. This process results in the creation of additional energy states in the hybrid materials system and thus allows electrons in the material to hop to different electronic states and emit different colors.

At the same time, the heated material changes in its physical form due to heat-induced melting and re-solidification of the agglomerated powder, resulting in the formation of periodic arrangements of carbon nanoparticles. The visible colors are also partly due to light scattering from these periodic arrangements.

The researchers also found that they are able to turn off, or dim, the fluorescence coming from the sample by applying an external electric potential. This, coupled with the ability to transfer the material onto flexible, transparent films, could potentially allow the “new” material that could be useful as a flexible and transparent multicolor fluorescence display.

“As the process is not limited by scale and is flexible, recovered carbon black powder could potentially be used for large-scale fluorescence displays,” says Sow Chorng Haur, a professor from the physics department at National University of Singapore.

“This provides a simple means to turn an affordable and abundant material into something useful and beautiful.”

The paper appears in Nano Research.

Source: National University of Singapore