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

A new form of real gold, almost as light as air

November 25, 2015

Researchers at ETH Zurich have created a new type of foam made of real gold. It is the lightest form ever produced of the precious metal: a thousand times lighter than its conventional form and yet it is nearly impossible ...

Moonlighting molecules: Finding new uses for old enzymes

November 27, 2015

A collaboration between the University of Cambridge and MedImmune, the global biologics research and development arm of AstraZeneca, has led researchers to identify a potentially significant new application for a well-known ...


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.