Polymer Material Registers Impacts


A team of researchers has developed a polymer-based material that changes color depending on the strength of impact.

The team's vision is to see the technology used to give a clear, visual indication of dangerous head injuries when used in protective headgear.

The Basis of the Research

Diagnosing whether someone has suffered head trauma at the time of an accident—whether for a player on the football field or a soldier near a bomb blast—is not a fast or easy process.

But a product that immediately changes color depending on how hard it is hit could help provide immediate detection of a serious head injury.

“If the force was large enough, and you could easily tell that, then you could immediately seek medical attention,” said Shu Yang, Ph.D. in a release from the American Chemical Society (ACS).

According to ACS, Yang’s team at the University of Pennsylvania used holographic lithography (HL) to create photonic crystals with structures carefully designed to give them a particular color, like an opal.

When a force as applied, the crystals’ internal structures changed and became deformed, changing the color.

Deforming the crystals with an applied force changed their internal structures, and also the crystal’s color, enabling medical personnel to readily identify damaging force on-site without additional tools.

Adapting the Process

The HL method of making these crystals is expensive, however, making it unsuitable for mass production, Yang said.

Her team opted for self-assembly and polymer-based materials that are cheaper to produce over a large area than the original HL method and, according to Younghyun Cho, Ph.D., a postdoctoral fellow in Yang’s lab, this adjusted procedure could be the path to commercialization.

In the new approach, they molded the polymer into a structure that worked in the same ways the photonic crystals did.

They tested the polymer material with the application of various levels of force and recorded the color change, seeing the results they were looking for.

 “We were able to change the color consistently with certain forces,” Yang said.

For example, with the approximate force of a sedan moving at 80 miles per hour crashing into a brick wall, the material changed from red to green. With a force equal to a speeding truck hitting the wall, they polymer turned purple, said Cho.

The polymer the team developed changes different colors based on the force of impact, which helps to indicate if it was strong enough to cause concussion.

“This force is right in the range of a blast injury or a concussion,” said Yang.

It is unclear whether the polymer material will continue to be molded or applied via another method.

In future studies, Yang said she plans to develop materials that can indicate how quickly a force is applied, which affects how damaging a particular trauma is on the brain.

Her team presented their research at the 250th National Meeting & Exposition of the ACS. The ACS is a nonprofit organization chartered by the U.S. Congress, the world’s largest scientific society, and a global leader in providing access to chemistry-related research.


Tagged categories: American Chemical Society; Asia Pacific; Coating chemistry; Coating Materials; EMEA (Europe, Middle East and Africa); Latin America; North America; Polymers; Research and development

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