Plasma etching of organic material: Combined effects of charged and neutral species

A model organic material, namely the 36-n-alkane hexatriacontane, was etched in a dissymmetrical parallel plate RF plasma reactor and a dual distributed electron cyclotron resonance (DECR) plasma reactor, in different O2-Ar mixtures. A specific attention was paid to the role of the ion bombardment, especially when its effect is combined with the chemically active species created in an oxygen discharge. The discharge was monitored by optical emission spectroscopy (OES). The modifications induced by plasma treatment on the structure of the material were analysed by Fourier transform infrared spectroscopy (FTIR), steric exclusion chromatography (SEC) and composition analysis. We found that the ion bombardment has not only a sputtering effect but also enhances the reaction rate of the chemical species on the layer surface. It appears that plasma treatment leads to cross-linking and recombination with molecules from the room atmosphere

Characterization of polypropylene surface treated in a CO2 plasma

The polypropylene modification in CO2 plasma mainly contributes to degradation, functionalization, and cross-linking. The degradation, whose rate is depending on CO2 dissociation and oxygen atom formation, is a quite slow reaction and it is associated with surface topography alteration, especially of the amorphous phase of the polypropylene. The surface roughness increases with the treatment duration and the amorphous phase is more degraded than the crystallized part. The functionalization, corresponding to an increase of the surface energy (57.3 mJ.m(-2) in 30 s), and to an oxidation (23 oxygen at.%) with the appearance of alcohol, ketone, and acid functions is a much faster phenomenon. Cross-linking takes also place during this type of treatment and will reinforce the stability of the modified surface

New surfaces with hydrophilic/hydrophobic characteristics in relation to (no)bioadhesion

The possibility of biosurfaces with high or low adhesiveness for protein, bacteria or eukaryotic cells is discussed. At the interface surface object/biological milieu, biocompatibility, (no) bioadhesion and (no) biocontamination are shown to be correlated with physico-chemical surface characteristics. First consequence is the (no) possibility of biofilm formation. Substrates with low surface energy could interact only with hydrophobic biomolecules. On substrates with high surface energy, a water monolayer spontaneously formed. Modification of a surface by plasma techniques is a way for engineering biomaterials. Plasma techniques are dry processes and more suitable for biomedical applications. In the field of biomaterial medical devices, in hygienic prevention of nosocomial diseases, in food packaging, the use of substrates with a very hydrophilic character may help to prevent the proliferation of cells and bacteria. Such a technique is so efficient that antibiotic molecules are not necessary. Therefore, surface engineering is a tool for modifying and adapting materials to specific biological applications

A Bottom-Up and Templateless Process for the Elaboration of Plasma-Polymer Nanostructures

International audienceIn this paper, the transition from smooth layer to nanostructured one during plasma deposition of polyaniline is demonstrated. The deposition mechanism at low discharge power allows obtaining a smooth layer with well-defined chemical structure while high discharge power gives a structured layer but does not preserve the monomer structure. A method giving the possibility to overcome these problems by combination of high- and low-power deposition is described. Obtained layers are investigated by FT-IR spectrometry, profilometry, and atomic force microscopy

Azobenzene-Containing Monolayer with Photoswitchable Wettability

International audienc

ToF-SIMS ability to quantify surface chemical groups: Correlation with XPS analysis and spectrochemical titration

High-density polyethylene (HDPE) and polypropylene (PP) films were analysed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) in a quantitative way in order to study chemical modifications produced by CO2 plasma surface treatments. Although there are many works devoted to the study of surface modification by plasma treatments, this contribution aims at proving the SIMS ability to quantify superficial functions. For that purpose, results obtained by spectrochemical titration (fluorescence labelling with thionine acetate), XPS measurement and ToF-SIMS analyses were compared. The results obtained with these three different techniques showed the same behaviour, i.e. a fast carboxylic functionalization of the polymer surface with the plasma treatment time. The good correlation between the spectrochemical titration and ToF-SIMS results brings out clearly the capacity of the ToF-SIMS technique to quantify surface chemical species. But this requires that we should be able to identify the secondary ions originating from the studied functions. Copyright (C) 2001 John Wiley & Sons, Ltd