Nitric Oxide Radical Trapping Analysis on Vacuum-Ultraviolet Treated Polymers

Wilken, Ralph; Holländer, Andreas; Behnisch, J.

doi:10.1021/ma9802071

Cited by 43 publications

(50 citation statements)

References 19 publications

(22 reference statements)

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“…Nitrogen atoms with one bond to oxygen like oximes have a N1s BE of about 400.5 eV. [25] The BE of nitrogen in a nitroso group (two bonds to oxygen) is equal to 403.7 eV. [26] However, a peak position at 402.5 eV is close to 402.8 eV which corresponds to nitrogen in amine oxides [27] and which is a reasonable intermediate in the oxidation of amines.…”

Section: Amino Groupsmentioning

confidence: 99%

TFAA chemical derivatization and XPS. Analysis of OH and NHx polymers

Pippig

Sarghini

Holländer

et al. 2009

Surface & Interface Analysis

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The determination of functional groups on complex polymer surfaces by X-ray photoelectron spectroscopy (XPS) can be improved considerably by derivatization reactions. Simple polymers containing hydroxyl groups or amino groups were investigated as reference materials for the derivatization with trifluoroacetic anhydride (TFAA).Poly(vinyl alcohol) (PVA), poly(hydroxyethyl methacrylate) (PHEMA), poly(vinyl butyral) (PVB), poly(allylamine) (PAAm), and poly(diallyl amine) (PDAAm) were derivatized using TFAA and analyzed with XPS. Polyethylene (PE) was used as an independent external reference for the binding energy (BE). Applying this procedure, the BE scales of all measurements were referenced to the carbon atoms of PE. It was found that the BE of the CF 3 component in the C1s region is different when bonded as an acetate or as an amide. The CF 3 BE is also influenced by the density of these groups in the polymer molecule. In TFAA-PVA, where every second main chain carbon atom carries a trifluoroacetate (TFAc) group, the BE is 294.3 eV while in TFAA-PVB with only isolated groups, the BE is 293.6 eV. The BE of the CF 3 component in the trifluoroacetamides (TFAAms) prepared from PAAm and PDAAm was found to be 292.5 and 292.3 eV, respectively. Compared with the analog fluorine free compounds, the BE is shifted toward higher values also for the ester carbon atom, the amide carbon atom, and the carbon atom to which the ester or amide is bonded.The data suggest that the gas phase reaction of TFAA with a polymer surface is diffusion limited. The actual ester or amide formation is a fast reaction and runs as a wave into the surface.

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Section: Amino Groupsmentioning

confidence: 99%

TFAA chemical derivatization and XPS. Analysis of OH and NHx polymers

Pippig

Sarghini

Holländer

et al. 2009

Surface & Interface Analysis

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“…The signal assigned to the open form of N-C pyrrolic ring at 401.7 eV [47], and new signals at 402. 7 eV corresponding to -C=N-OH, at 403.8 eV assigned to -C-N=O group can be identified [43,48,49]. The analysis of both C and N 1s core signals before and after degradation confirmed irreversible changes in the carbon structure.…”

Section: Electrochemical Stabilitymentioning

confidence: 81%

Electrochemical stability of the polymer-derived nitrogen-doped carbon: an elusive goal?

Cong

Radtke

Stumpf

et al. 2015

Mater Renew Sustain Energy

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Nitrogen-doped carbon is a promising metalfree catalyst for oxygen reduction reaction in fuel cells and metal-air batteries. However, its practical application necessitates a significant cost reduction, which can be achieved in part by using new synthetic methods and improvement of catalytic activity by increasing the density of redox active centers. This can be modulated by using polymer as the carbon and nitrogen sources. Although, superior catalytic activity of such N-doped C has been investigated in details, the electrochemical long-term stability of polymer-derived doped-carbon is still unclear. Herein, in this study we generated N-doped carbon from the most recommended polymer that is comparable to the state-of-the-art materials with porosity as high as 2,086 m 2 g -1 and a nitrogen doping level of 3-4 at.%, of which 56 % is pyrrolic N, 36.1 % pyridinic and *8 % graphitic. The electrochemical characterization shows that N-doped carbon is catalytic toward oxygen reduction in an alkaline electrolyte via a favorable four-electron process, however, not stable under long-term potential scanning. The irreversible electrochemical oxidation of this material is associated with the presence of a significant content or pyrrolic and pyridinic N close to the edge of the carbon network originating from the polypyrrole precursor. These structures are less stable under operating electrochemical potential. The role of polypyrrole as the precursor of N-doped carbons has to be carefully revised since it supplies sufficient number of catalytic sites, but also generates unstable functionalities on the carbon surface.

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“…4) can be explained by the reduction of the concentration of active chains as a result of the irreversible termination of the chain radicals by 9N2O species. Nitric oxide can react only with carbon radicals 27) . In addition to the low dissociation energy of the [PS-(4-oxo-TEMPO)]-adduct, the short induction period in the 4-oxo-TEMPO/BPO-system ( Fig.…”

Section: Resultsmentioning

confidence: 99%

4-Oxo-2,2,6,6-tetramethylpiperidine-N-oxyl (4-oxo-TEMPO)- and 4-acetamido-2,2,6,6-tetramethylpiperidine-N-oxyl (4-acetamido-TEMPO)-controlled free radical polymerization of styrene

Han¹,

Drache²,

Baethge³

et al. 1999

Macromol. Chem. Phys.

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SUMMARY:The controlled free radical polymerization of styrene initiated with benzoyl peroxide (BPO) in the presence of 4-oxo-2,2,6,6-tetramethylpiperidine-N-oxyl (4-oxo-TEMPO) as well as 4-acetamido-2,2,6,6-tetramethylpiperidine-N-oxyl (4-acetamido-TEMPO) at 135 8C was studied. The obtained results were compared with those of the 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) controlled free radical polymerization of styrene. Up to a nitroxide/BPO molar ratio of 1.5 : 1, the conversions in the 4-oxo-TEMPO/BPO-system are higher than the conversions in the other systems. The conversion in the 4-acetamido-TEMPO/BPOsystem is lower than that in the 4-oxo-TEMPO/BPO-system, but higher than the conversion in the TEMPO/ BPO-system under the same reaction conditions. The shortest induction periods were observed in the 4-oxo-TEMPO/BPO-system, while the longest induction periods were observed in the TEMPO/BPO-system. Except in the lower region of nitroxide/BPO molar ratio (1 : 1), the number-average molecular weight (M

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Nitric Oxide Radical Trapping Analysis on Vacuum-Ultraviolet Treated Polymers

Cited by 43 publications

References 19 publications

TFAA chemical derivatization and XPS. Analysis of OH and NHx polymers

TFAA chemical derivatization and XPS. Analysis of OH and NHx polymers

Electrochemical stability of the polymer-derived nitrogen-doped carbon: an elusive goal?

4-Oxo-2,2,6,6-tetramethylpiperidine-N-oxyl (4-oxo-TEMPO)- and 4-acetamido-2,2,6,6-tetramethylpiperidine-N-oxyl (4-acetamido-TEMPO)-controlled free radical polymerization of styrene

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