X-ray photoelectron spectroscopy (XPS) is a typical method used for the chemical characterization of material surfaces.
In recent years, major developments, including imaging, have resulted in a wider range of applications. Suppliers and manufacturers of technical and commercial textiles are now using XPS to develop and optimize different types of surface coating and treatment needed by consumers and industry.
Plasma Treatment of Medical Textiles
Polypropylene and polyester are polymer meshes which are used for repairing hernias and other soft tissue defects. Although the utilization of mesh materials has significantly improved this type of surgery, their implantation is associated with extreme infection rates. Therefore, improving the surface properties of these meshes can lower the infection rates.
The use of atmospheric pressure and low pressure plasmas for the coating and functionalization of textile surfaces is becoming increasingly important. The main areas where plasma process is used for new textile products include the development of repellent surfaces to limit/prevent the adhesion of bacteria/biofilms in surgical and hygiene applications.
This article describes the functionality of XPS in examining the integrity of a polyethylene glycol (PEG) plasma coating on a polypropylene (PP) mesh.
XPS of PEG Coated PP Mesh
XPS spectroscopy can be used to detect the PEG coating in a survey or elemental spectrum by the presence of oxygen. An example of this is shown in Figure 1. Only carbon is identified from an untreated PP surface.
Figure 1. XPS survey spectrum from PEG-coated PP.
The presence of chemical states is examined by high resolution C 1s spectra. These spectra also indicate the degree of the surface treatment.
The PEG coating; rich with C-O, dominates for meshes with excellent PEG coverage. A large C-O element, at a binding energy of 286.5 eV, is shown in Figure 2a. This is completely different to the higher C-C element; characteristic of the PP mesh, for lower coating coverage. A much higher C-C element, at a binding energy of 285.0 eV, is shown in Figure 2b.
Figure 2a. C 1s XPS spectrum from PP mesh with good PEG coverage.
Figure 2b. C 1s XPS spectrum from PP mesh with poor PEG coverage.
XPS imaging, in combination with the spectroscopy, is essential for evaluating the coating coverage. This is shown in Figure 3 for a region of mesh treated with plasma, where the PEG-based coating is not complete and the PP mesh can be easily seen.
Figure 3. Overlay of C-C and C-OI chemical state images from a PEG-based coating on a PP mesh. Green regions = good coating coverage (C-O), red regions = poor coating coverage (C-C). Image dimensions = 0.8 x 0.8 mm.
The integrity of the PEG coating can be measured as a function of the plasma treatment factors. Therefore, XPS can help improve the PEG coating for the highest anti-adhesive properties. The XPS technique can also be employed to measure the surface modification effects of sterilization (i.e. ethylene-oxide, gamma irradiation, autoclaving), or for storage/packaging on the PEG coating.
As the coating of surgical meshes poses a major challenge to plasma technologists, XPS can play a significant role in the development of this coating technology.
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This information has been sourced, reviewed and adapted from materials provided by Kratos Analytical Ltd.
For more information on this source, please visit Kratos Analytical Ltd.