Features of mechanism of free radical initiation in polymers under exposure to nitrogen oxides

Abstract

The mechanism of interactions of NO, NO2, NO3 as well as dimers of NO2 with functional groups of organic molecules and polymers is considered. It is shown that nitrogen oxides are active initiators of radical reactions as a result of which various molecular products of nitration and stable nitrogen‐containing radicals are formed. Features of the initiation mechanism determining the composition of molecular and radical products of conversions of the compounds on exposure to nitrogen oxides have been revealed. Copyright © 2008 John Wiley & Sons, Ltd.

Stability of Zeolitic Imidazolate Frameworks in NO2

“…Formation of nitrites, nitrates, nitro-, and nitramine groups have been reported during gas-phase reactive adsorption of NO 2 on a variety of carbonaceous materials at ambient temperature. ,,,− The presence of imidazoles in ZIFs creates the strong possibility of similar mechanisms. The strong decrease in aromatic and aliphatic C–H stretching and bending vibrations in all three ZIFs upon dry NO 2 exposure, and the presence of adsorbed HONO (1700 cm –1 stretch), are consistent with the free radical H-abstraction mechanism.…”

Volumetric Photopolymerization Confinement through Dual-Wavelength Photoinitiation and Photoinhibition

“…As summarized in Scheme 1, this UV-induced photoinhibition was attributed to the photolysis of BN, generating nitric oxide (1) that in turn affords a nitroso spin trap upon chain termination (2). 31 This spin trap subsequently terminates a second propagating polymer chain (3), and the generated nitroxide radical terminates another active radical center (4). Thus, although the alkoxy radical also generated by alkyl nitrite photolysis acts to initiate polymerization (5), one photolysis event yields a net two termination events.…”

“…The photochemical decomposition of organic nitrites results in the formation of nitric oxide, an efficient inhibitor of radical-mediated polymerizations, and alkoxide radicals capable of polymerization initiation. As summarized in Scheme , this UV-induced photoinhibition was attributed to the photolysis of BN, generating nitric oxide (1) that in turn affords a nitroso spin trap upon chain termination (2) . This spin trap subsequently terminates a second propagating polymer chain (3), and the generated nitroxide radical terminates another active radical center (4).…”

Effect of Three-Dimensional-Printed Thermoplastics Used in Sensor Housings on Common Atmospheric Trace Gasses

“…To relate our experimental results to real-world air quality measurements, we calculated the difference in VOC, NO, and NO 2 concentrations using this study’s off-gassing and reaction rates for two sets of theoretical scenarios. The first (called moderate and detailed in Table S14 ) used an FDM area of 118 cm 2 , VOC concentration of 41 ppb, NO/NO 2 concentrations of 35 ppb, and residence time of either 2 or 75 s. The second (called worst case and detailed in Table S15 ) used an FDM surface area of 1478 cm 2 , VOC concentration of 10 ppb, NO concentration of 600 ppb, NO 2 concentration of 200 ppb, and residence time of either 2 or 75 s. Although some concentrations used in these scenarios are lower than our experimental conditions, Davydov et al [ 36 ] discussed that polymeric degradation at low gas concentrations could be extrapolated from results at higher gas concentrations. Consequently, we assumed constant VOC off-gassing rates and NO/NO 2 reaction rate parameters ( k and ).…”

“…To the best of our knowledge, no studies have examined carbon monoxide (CO), carbon dioxide (CO 2 ), nitrogen monoxide (NO), and nitrogen dioxide (NO 2 ) gas reactivity with ABS, PLA, PETG, PC, and PVDF. However, multiple studies have examined the reaction between nitrogen oxides (NO x ) and various thermoplastics, and these studies can shed light on NO x reactions with different groups of thermoplastics [ 36 , 37 , 38 ]. NO 2 is a strong oxidizing agent [ 38 , 39 ].…”