Eric Brendlé

Comparison of the surface properties of graphite, carbon black and fullerene samples, measured by inverse gas chromatography

Three types of carbon were examined by inverse gas chromatography (IGC), at infinite and finite concentration conditions: graphite, carbon black and fullerene (C60) samples. Those samples differ by their structure and also by their surface properties (existence of defects, of polar surface groups...): surface free energy characteristics and surface energetic heterogeneity. IGC allows to determine in part these properties and evidences strong differences amongst the 3 carbons.

Inverse gas chromatography investigation of the surface properties of cellulose

Cellulose samples differing in origin and crystallinity were examined by inverse gas chromatography (IGC). Surface energy characteristics such as the apparent dispersive component of the surface energy and acid-base properties, and also nanomorphology indices of the different cellulose samples, were assessed. The influence of humidity on these properties was demonstrated. A decrease of 10-20% of the interaction potential was detected. Crystalline cellulose is the most sensitive to the presence of adsorbed water, which possibly disorders its surface structure. IGC appears to be an appropriate method for the evaluation of the surface characteristics of cellulose. However, care has to be taken when trying to understand differences in surface properties between various cellulose samples, since IGC is very sensitive to minor variations in surface characteristics.

Variation of the surface properties of nickel oxide upon heat treatment evidenced by temperature programmed desorption and inverse gas chromatography studies

The surface properties (dispersive component γSdof surface energy and surface nanomorphology) of nickel oxide samplessubmitted to heat treatments up to 550°C were examined bytemperature programmed desorption (TPD) and inverse gaschromatography (IGC) methods. It is shown that the variation ofγSd is complex, first increasing as thetemperature reaches about 300°C, then decreasing and goingagain through a maximum, of lower amplitude, for a treatmenttemperature of about 600°C. These variations follow closelythe TPD curves that related the rate of H2O and, in a much lesserextend of CO2 releases as the heat treatment temperature augments.The surface nanomorphology changes also during this treatment. TheNiO surface becomes very interactive when treated around 250°C. The determination of the adsorption energy distributioncurves (energetic heterogeneity) clearly demonstrates the change insurface properties and development of the population of highadsorption energy sites. Rehydration of the sample treated at 300°C was not possible under our experimental conditions.

Study of the interaction polybutadiene/fillers using inverse gas chromatography.

In this study, the coupling of IGC-ID analysis and carbon blacks impregnation with increasing ratios of polymer allow us to highlight the affinity of the polymer to the solid surface. The variations of the dispersive component of the surface energy and of the nanomorphology index are monitored versus the degree of carbon black impregnation. A clear correlation between the decrease in the dispersive component of the surface energy and the increase in the nanomorphological index is observed. The PBu macromolecules shield progressively the slot shaped sites on the carbon blacks surface. IGC reveals clear differences in surface properties between CB of different grades.

Inverse gas chromatography investigation of the surface characteristics of stainless steel tubing

Inverse gas chromatography (IGC) was used to determine the surface properties (dispersive component of surface energy and surface area) developed by the oxide layers of stainless steel chromatographic columns. Clear differences are noted depending on the treatments (passivation, electropolishing, polyacrylic acid coating) of the columns. The passivated column possesses higher surface energy than the electropolished column. The surface area developed by the oxide layer on the inner wall of the passivated tubing exceeds significantly the one of the electropolished tubing. The polyacrylic acid coating diminishes both the dispersive and polar interaction potentials of the treated tubing. IGC appears to be a very suitable method for the characterization of the properties of the metallic surfaces.