Analysis of functional groups on the surface of plasma-treated carbon nanofibers

Abstract

Plasma chemically modified carbon nanofibers were characterized by X-ray photoelectron spectroscopy with regard to the content of carbon, oxygen, and nitrogen and the contribution of carboxylic groups or ester, carbonyl and hydroxylic groups or ether on the surface. Unfortunately, X-ray photoelectron spectroscopy only provides an average value of the first 10 to 15 molecular layers. For comparison, depth profiles were measured and wet chemical methods were applied to estimate the thickness of the functionalized layer and the distribution of oxygen-containing functional groups within the near-surface layers. The results indicate that the fiber surface is covered by a monomolecular oxygen-containing layer and that plasma treatment allows a complete oxygen functionalization of the uppermost surface layer. The best conditions for plasma treatment found within the set of parameters applied to generate complete functionalization are: plasma gas O(2)/Ar ratio 1:1, gas pressure 1-1.5 hPa, plasma power 80 W, treatment time >or= 5 min. Additionally, three quick and easy methods are presented to estimate the efficiency of plasma treatment with regard to surface functionalization: pyrolysis, contact angle measurements, and light permeability measurements of aqueous carbon nanofiber suspensions.

Carbon States in Carbon-Encapsulated Nickel Nanoparticles Studied by Means of X-ray Absorption, Emission, and Photoelectron Spectroscopies

“…As for Ni@C (1), the prominent peak at 284.5 eV reveals C-C interactions. The additional peaks in the C 1s XPS spectrum of Ni@C (2) at 285.5 eV, 286.6 eV, and 288.8 eV can be identified as hydroxyl (OH), carbonyl (C=O), and carboxyl (O=C-OH) groups attached to the carbon atom in Ni@C, [31][32][33][34] respectively, as it is shown in…”

Plasma Modification of Carbon Nanotubes and Bucky Papers

“…In the literature, different approaches have been discussed concerning the deconvolution of the C1s peak of CNTs. Some use a graphite peak shape for the large peak at 284.6 eV with the tail at the high energy binding site,26,33,34 others distinguish between sp 2 ‐ and sp 3 ‐carbon at 284.6 eV (C1) and at 285.1 eV (C2), respectively 35,36. The peaks with binding energies higher than 290 eV have been interpreted as π – π * transitions (shake ups)37 or have been neglected 38.…”

Surface Modification of Electrospun Polycaprolactone Nanofiber Meshes by Plasma Treatment to Enhance Biological Performance

“…The samples treated at these conditions also presented the highest oxygen content (XPS analysis), indicating the importance of the surface chemistry for cell adhesion. The oxygen atoms at the surface may be part of the carbonyl, carboxyl, ester, or hydroxyl groups 35. However, it is not clear which of these groups is the most effective in influencing the cell–biomaterial interaction.…”