Detection of ultra trace concentrations of explosives using fluorescent polymers
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“Detection of Ultra-Trace Concentrations of Explosives Using Fluorescent Polymers”. Presented By Allen Luebbe. Overview. Brief history of explosives General explosive knowledge Energy of explosives Chemical fingerprints New fluorescent polymers. History of Explosives.

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Detection of ultra trace concentrations of explosives using fluorescent polymers

“Detection of Ultra-Trace Concentrations of Explosives Using Fluorescent Polymers”

Presented By Allen Luebbe


Overview
Overview Using Fluorescent Polymers”

  • Brief history of explosives

  • General explosive knowledge

  • Energy of explosives

  • Chemical fingerprints

  • New fluorescent polymers


History of explosives
History of Explosives Using Fluorescent Polymers”

  • 1242 Roger Bacon publish optimum recipe for gunpowder

  • 1659 first ammonium nitrate synthesized by J.R. Glauber

  • 1846 Italian chemist Ascanio Sobrero synthesized nitroglycerine

  • 1866 Alfred Nobel invented dynamite

  • 1955 invention of ANFO

  • 2000 Philip Eaton synthesized octanitrocubane


For a chemical to be an explosive it must exhibit all of the following
For A Chemical To Be An Explosive, It Must Exhibit All Of The Following

  • Formation of gases

  • Evolution of heat

  • Rapid rate of reaction


Explosives
Explosives The Following

  • Most explosives are organic compounds and contain multiple nitro groups

  • In addition to these compounds explosives properties they are also toxic to humans


Categories of explosives
Categories Of Explosives The Following

  • High Explosives

    • Detonate (1000 to 8500m/s)

    • Differentiated by sensitivity

      • Primary - extremely sensitive to impact, heat, and friction

      • Secondary - less sensitive

  • Low Explosives

    • Used as propellants

    • Burn rapidly (up to 400m/s)


Nitro group
Nitro Group The Following

  • Many nitro compounds are unstable

  • The nitrogen atom is positively charged and each oxygen atom has a partial negative charge.

  • The nitro group has a powerful attraction for electrons


Why do nitro groups lead to unstable compounds
Why do nitro groups lead to unstable compounds? The Following

  • Nitrogen has charge of +1 and nitro groups have a strong tendency to withdraw electrons from other parts of the compound


High explosives
High Explosives The Following


Octanitrocubane
Octanitrocubane The Following


Energy of explosives
Energy of Explosives The Following

  • Chemical explosives must provide a means to transfer heat energy to mechanical energy


Energy of explosives1
Energy of Explosives The Following

  • Total amount of energy released in an explosive reaction is called the heat of explosion

  • Calculated by comparing heats of formation before and after the reaction

    ∆E = ∆Ef(reactants) - ∆Ef(products)


Heat of explosion for tnt
Heat Of Explosion for TNT The Following

∆E = ∆Ef(reactants) - ∆Ef(products)

∆E = ∆Ef(-54.4kJ/mol) - ∆Ef(-670.8kJ/mol)

∆E = 616.4 kJ/mol

∆E > 0, rxn is exothermic

(616.4 kJ/mol)(1000 J/1 kJ)(1 mol/227 g) = 2175 J/g


TNT The Following

  • Most commonly used explosive in landmines is TNT

  • Mines containing TNT or a mixture of TNT and other explosives accounts for 80% of all landmines manufactured world wide

  • 90% of landmines used in military operations contain TNT



Chemical fingerprints
Chemical Fingerprints The Following

  • Explosives emit chemical signatures called fingerprints

  • Each explosive has its own distinct chemical fingerprint


Chemical fingerprint of tnt
Chemical Fingerprint of TNT The Following

  • Military grade TNT contains chemical contaminants

  • Contaminants are produced during the synthesis of TNT

  • Contaminants in TNT usually have a higher equilibrium vapor pressure than TNT

  • Examples of contaminants in TNT are dinitrotoluenes


Detecting explosives
Detecting Explosives The Following

  • Canines: canines can detect minute quantities for a variety of explosives.

  • Chemical Sensor: molecules are collected on a fiber and "ion mobility spectrometer" identifies type of explosive.

  • Neutron Beam: When neutrons contact contaminant, they instantly produce high energy gamma rays. Explosives are identified from energy of gamma rays.

  • Lasers: The interaction of laser radiation with traces of explosive causes micro bursts. Explosives are identified from light generated by bursts.


Chromophore
Chromophore The Following

  • chemical group capable of selective light absorption resulting in the coloration of certain organic compounds.


Polymer detector
Polymer detector The Following


Advantages of polymer detector
Advantages of Polymer detector The Following

  • Can detect concentrations of TNT in the parts per quadrillion

  • A single molecular binding event can change the fluorescence of an entire chain instead of just one molecule

  • Sensitivity of devices can be increased up to 10,000 times

  • Polymer receptor sites can be tuned to interact with only certain types of molecules


Synthesis of 5 bromo pyridin 2 yl 4 bromo thiophen 2 ylmethylene amine
Synthesis of (5-bromo-pyridin-2-yl)-(4-bromo-thiophen-2-ylmethylene)-amine


Polymerization
Polymerization (5-bromo-pyridin-2-yl)-(4-bromo-thiophen-2-ylmethylene)-amine


References
References (5-bromo-pyridin-2-yl)-(4-bromo-thiophen-2-ylmethylene)-amine

  • http://www.biochemtech.uni-halle.de/PPS2/projects/jonda/chromoph.htm

  • http://www.mn-net.com/web/

  • Sheats, J. R. Science. 1997, 277, 191-192.

  • http://www.nomadics.com/Landmine_Detector/Brochures_white_papers/uxo2001.pdf

  • Chen, L; McBranch, D.; Wang, R.; Whitten, D. Chem Phys Lett., 330, 27-33, 2000.

  • http://www.fas.org/man/dod-101/navy/docs/es310/chemstry/chemstry.htm

  • http://www.umich.edu/~navyrotc/NS202/ExplosivesandWarheads.ppt


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