Showing papers by "Michel Delamar published in 1996"
TL;DR: Aminopropyltriethoxy silane (APS) adsorption on quartz has been monitored by XPS and found to be of the Langmuir type as mentioned in this paper.
96 citations
TL;DR: In this paper, the pH effect on the relaxation of polyaniline for the first redox system was investigated and it was shown that the relaxation phenomenon is affected by pH only at pH 2.
27 citations
TL;DR: In this article, the acid-base properties of ammonia plasma-treated polypropylene (APTPP) were characterized by X-ray photoelectron spectroscopy (XPS) in conjunction with the molecular probe technique and using chloroform (TCM) as a reference Lewis acid.
Abstract: Acid-base properties of ammonia plasma-treated polypropylene (APTPP) were characterized by X-ray photoelectron spectroscopy (XPS) in conjunction with the molecular probe technique and using chloroform (TCM) as a reference Lewis acid. It is shown that TCM is retained by the basic surfaces of APTPP but not by the untreated PP. The retention of TCM is shown to be entirely due to the formation of TCM:APTPP acid-base complexes. This is supported by the C12p3/2 binding energy (BE) and the shape of the Cl2p peak from the adsorbed TCM. ΔHAB, the heat of TCM:APTPP acid-base interaction was found to be in the range of 3.1–4.3 kcal/mol using a published Cl2p3/2 BE−ΔHAB correlation. This ΔHAB compares remarkably well with the values of 4.3–4.9 kcal/mol determined for TCM:amine complexes, and shows indeed that TCM is complexed by nitrogen containing basic groups grafted at the surface. However, the TCM/N ratio has an optimal value up to 1 second of plasma treatment and then decreases sharply, showing that less specific interaction sites are accessible at the surface for longer treatment times. This parallels previous findings about the metallization of APTPP by aluminium which was found to be optimal for treatment times lower than 1 second in our experimental conditions. This work shows that XPS can now indeed be used to quantitatively assess the acid-base properties of modified polymer surfaces.
19 citations
TL;DR: In this article, it is suggested that the slow relaxation phenomenon in polyaniline is due to a change of structure of the double layer under polarization, which is the main reason for the peak shift characteristic of the so-called relaxation effect in addition to structural changes.
13 citations
TL;DR: In this paper, the authors used SCF calculations to determine the possible interaction sites in model structures of the polyimide pyromellitic dianhydride-oxydianiline (PMDA-ODA) interacting with Ti atoms.
12 citations
11 citations
TL;DR: Solutions of solvated electrons in the presence of magnesium offer many advantages for the surface treatment of PTFE when compared to the classical solutions of Solvated EDEs in the absence of alkalis: the polymer remains white instead of black, its surface is not destroyed and presents a controlled hydrophilic character as discussed by the authors.
9 citations
01 Jan 1996
TL;DR: In this paper, the authors examined the interface between evaporated Ti and PMDA/ODA polyimide using several techniques and showed that the failure is of cohesive type in the polymer layer.
Abstract: The interface between evaporated Ti and PMDA/ODA polyimide is examined using several techniques. The formation of small TiO2 particles at this interface (15 to 40 μm diameter, ca.30 nm thickness, covering about 6% of the interfacial area) is demonstrated. The failure is of cohesive type in the polymer layer. When the residual pressure during Ti evaporation is increased, the number of TiO2 particles increases, adhesion of the Ti layer is lowered and the locus of failure is closer to the metal layer. When an oxygen plasma treatment is performed onto PMDA/ODA prior to Ti evaporation, the failure mode remains cohesive in the polymer layer. However the failure occurs at the modified/unmodified polymer limit. Ab initio (SCF) calculations were finally performed on models of the PMDA‐ODA polyimide in interaction with one Ti atom, in order to determine the most favorable interaction sites of this metal with the polymer. The most favorable interaction corresponds to the formation of a complex between Ti and the aromatic ring of the PMDA unit. Other possible sites of interaction are, in decreasing order of stability: the heterocycle of PMDA, the ≳C=O groups of PMDA and the ODA aromatic ring. Calculations of the core MO energies for the various model situations, show that it is not possible to account for the low energy C1s peak observed at ca.282 eV. Introduction in the model of a Ti atom bonded to one of the aromatic carbons permits to account for this peak. Thus, the existence of Ti‐C bonds in the polyimide‐Ti system is clearly confirmed.
3 citations
01 Jan 1996
TL;DR: In this paper, the study of PMMA adsorption on some conducting polypyrroles (PPys) using a variety of surface analytical techniques was reported. But the results of the experiments were limited to a single surface.
Abstract: The study of PMMA adsorption on some conducting polypyrroles (PPys) using a variety of surface analytical techniques is reported. PMMA adsorption was monitored by X‐ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectroscopy (ToF‐SIMS) and inverse gas chromatography (IGC). XPS and ToF‐SIMS permit to determine the surface composition of PMMA‐coated PPy surfaces vs the solvent nature, temperature and the PPy dopant anion. Both techniques show that acid‐base interactions may govern PMMA adsorption. IGC was used to determine the coating morphology by monitoring the surface energy of the coated PPy powders. It is suggested that homogeneity of PMMA coatings increases with decreasing solvent power. Preliminary atomic force microscopy (AFM) results on PMMA films cast on flat PPy surfaces confirm the IGC observation.