Ultra-sensitive polymer detects explosive devices

June 5, 2013 by Anne Ju
Ultra-sensitive polymer detects explosive devices
Will Dichtel, assistant professor of chemistry, and graduate student Deepti Gopalakrishnan hold samples of their polymer that uses fluorescence to detect the explosive RDX. Credit: Jason Koski/University Photography

(Phys.org) —A chemical that's often the key ingredient in improvised explosive devices (IEDs) can be quickly and safely detected in trace amounts by a new polymer created by a team of Cornell chemists.

The , which potentially could be used in low-cost, handheld explosive detectors and could supplement or replace bomb-sniffing dogs, was invented in the lab of William Dichtel, assistant professor of chemistry and . The work was published online in May in the Journal of the American Chemical Society.

RDX, short for research department explosive, is an common in military and that is also a favorite of bomb-making terrorists. It requires a detonator to explode, but when detonated, it's more powerful than TNT. What's more, RDX's is 1,000 times lower than TNT's, making it almost impossible to detect without direct contact with a concentrator, like the swabs used at airport security.

Dichtel and graduate student Deepti Gopalakrishnan made a polymer that uses fluorescence to quickly and accurately ascertain whether RDX is present on a surface or in the air.

"One of the goals is to make detectors that can detect not just explosives on someone's hands, but in the cloud around them," Dichtel said – much like the surrounding Charlie Brown's friend Pigpen, he said. "If someone had an IED in their bag, it would be nice to not have to open it."

The researchers' work builds on a previously established technology that uses "fluorescence quenching" as the basis for detecting TNT; in the presence of the explosive, the polymer's fluorescence shuts off.

The polymer has a random, cross-linked structure that allows it to absorb light and transport the resulting energy throughout its structure. After a certain period of time, the polymer releases this energy as light, a process known as fluorescence. If the energy encounters a molecule of explosive as it travels through the polymer, it can be converted into heat instead of light, which causes the polymer to stop glowing. This design allows the polymer fluorescence to sense extremely small amounts of the explosive of interest, enabling identification of IEDs or people who have recently handled them.

The experiments also involved testing a host of other chemicals, such as those found in lipstick and sunscreen, to rule out false positives.

Dichtel's general research interest is in new kinds of polymers, particularly two-dimensional polymers, which are extremely orderly in their molecular pattern, like a city grid. While attempting to discover a new two-dimensional polymer, the researchers found this material, which does not have the same type of orderly structure, but turned out to be a perfect match for RDX.

Explore further: New device exposes explosive vapors

More information: pubs.acs.org/doi/abs/10.1021/ja402668e

Related Stories

New device exposes explosive vapors

August 15, 2011

Decades after the bullets have stopped flying, wars can leave behind a lingering danger: landmines that maim civilians and render land unusable for agriculture. Minefields are a humanitarian disaster throughout the world, ...

Explosives vapor detection technology: The new 'sniff test'

February 21, 2013

(Phys.org)—A quick, accurate and highly sensitive process to reliably detect minute traces of explosives on luggage, cargo or travelling passengers has been demonstrated by scientists at the Department of Energy's Pacific ...

Physicists discover a new kind of friction in the nanoworld

May 15, 2013

Whether in vehicle transmissions, hip replacements, or tiny sensors for triggering airbags: The respective components must slide against each other with minimum friction to prevent loss of energy and material wear. Investigating ...

Recommended for you

Findings illuminate animal evolution in protein function

July 27, 2015

Virginia Commonwealth University and University of Richmond researchers recently teamed up to explore the inner workings of cells and shed light on the 400–600 million years of evolution between humans and early animals ...

New polymer able to store energy at higher temperatures

July 30, 2015

(Phys.org)—A team of researchers at the Pennsylvania State University has created a new polymer that is able to store energy at higher temperatures than conventional polymers without breaking down. In their paper published ...

How to look for a few good catalysts

July 30, 2015

Two key physical phenomena take place at the surfaces of materials: catalysis and wetting. A catalyst enhances the rate of chemical reactions; wetting refers to how liquids spread across a surface.

Yarn from slaughterhouse waste

July 29, 2015

ETH researchers have developed a yarn from ordinary gelatine that has good qualities similar to those of merino wool fibers. Now they are working on making the yarn even more water resistant.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.