Inverse gas chromatography and acid-base interactions

Some relations between the net retention volume and the acid-base characteristics of the adsorbent are discussed in Inverse gas chromatography and acid-base interactions. 

Abel M-L, Watts JF (2005b) Inverse gas chromatography and acid-base interactions. In Packham DE (ed) Handbook of adhesion. Wiley, Chichester, pp 255-257 ASTM (2002) F 22-02 Standard test method for hydro-phobic surfece films by the water break test. ASTM, West Conshohocken, PA, USA Baer DR, Lea AS, Cazaux J, Geller JD, Hammond JS, Kover L, Powell CJ, Seah MP, Suziki M, Wolstenholme J, Watts JF (2010) J Elec Spec 176 80-94 Binnig G, Rohrer H, Gerber Ch, Weidel E (1982) Phys Rev Lett 49 57... 

Berg has provided a wide-ranging discussion of a range of methods - many described as tedious - by which acid-base interaction can be obtained. In addition to the method of Fowkes, considered above, two others are described Inverse gas chromatography and the contact angle method introduced by Good, Chaudhury and van Oss, which involves Acid-base surface energy parameters. 

Extending work done previously (1 - 2), the purpose of this paper is to examine how these characteristics could be determined using inverse gas chromatography (IGC) and to what extent these acid/base interactions are relevant to the description of the fibre-matrix interface. 

Inverse gas chromatography at infinite dilution appears to be a powerful tool for studying the surface properties of carbon fibres and polymer matrices. The use of alkane probes and acid/base probes allows the characterization of the surfaces in terms of their London dispersive component of surface energy and their acid/base or acceptor/donor characteristics. A strong correlation was obtained between fibre-matrix adhesion, measured by a destructive fragmentation technique, and the level of acid base interactions calculated from the chromatographic analysis. 

Inverse Gas Chromatography. The IGC results followed from measuring the retention times of the probe molecules injected into the columns packed with the fiber or coated with the polymer. To measure the dispersive interactions, the non-polar n-alkane probes were used. For the acid/base (or non-dispersive) interactions of the fibers, CHCl, THF, and EA were used. On the other hand,... 

Inverse gas chromatography involves the sorption of a known probe molecule (adsorbate, vapour) and an unknown adsorbent stationary phase (solid sample). IGC may be experimentally configured for finite or infinite dilution concentrations of the adsorbate. The latter method is excellent for the determination of thermodynamic properties such as surface energies and Lewis acid-base parameters. Measurements in this range are extremely sensitive due to the low concentration regime where the highest energy sites of the surface interact with the probe molecules. 

Several techniques are used to determine and interpret acid-base interactions. These include contact angle, inverse gas chromatography, IGC, Fourier transform infrared, FTIR, and X-ray photoelectron spectroscopy, XPS. These methods, as they are applied to solvents... 

ABSTRACT. The paper examines the influence of interactions at polymer surfaces and interfaces on the properties of polymer systems, with emphasis on acid/base interactions. The method of inverse gas chromatography is used to evaluate the donor-acceptor interaction potential of components in polymer systems. The usefulness of the interaction parameters is established by their ability to rationalize diverse properties of polymer systems, including the adsorption of polymers on pigments, and the effectiveness of thermal stabilizers in pigmented polymers. Various strategies for controlling surface and interfacial interactions in polymer systems are reviewed, with emphasis placed on the ability of polymers to adopt various surface orientations and compositions. TTiese inherent surface modification effects are attributed to thermodynamic driving forces, and are shown to influence polymer adhesion, barrier and other properties dependent on surface and interfacial forces. 

A concern for interactions requires the availability of methods able to describe them quantitatively. The first portion of this article examines approaches to the determination of component interactions, with emphasis on the technique of inverse gas chromatography (IGrC), and on the use of acid/base concepts in that context. A corollary to a concern for interactions, is the ability to control them beneficially. The second portion of this article... 

More recently, it has been shown, in particular by Fowkes and co-workers [2,6,7], that electron acceptor and donor interactions, according to the generalized Lewis acid-base concept, could be a major type of interfacial forces between two materials. This approach is able to take into account hydrogen bonds which are often involved in adhesive joints. Inverse gas chromatography at infinite dilution for example is a well adapted technique [8-10] for determining the acid-base characteristics of fibres and matrices. Retention data of probes of known properties, in particular their electron acceptor (AN) and donor (DN) numbers according to Gutmann s semi-empirical scale [11], allow the determination of acid-base parameters, and Kj), of fibre and matrix surfaces. It becomes then possible to define a "specific interactions parameter" A at the fibre-matrix interface, as the cross-product of the coefficients and Kq of both materials [10,11] ... 

In all of them the acid-base interactions are fundamental. Their evaluations can be based on thermodynamic surface properties such as the work of adhesion/pH diagrams and inverse gas chromatography. 

Figure 5.24 shows the effect of oxidation on dispersive and polar components of surface free energy. Carbon fibers were exposed to plasma treatment in the presence of various ratios of CF4 and O2. The untreated sample and the samples exposed to a substantial concentrations of oxygen show increase in the polar component. High concentrations of CF4 gas reduced its dispersive component and converted the surface to a PTFE-like material as confirmed by XPS studies. " Acid-base interaction which results from polar interaction can be predicted from the inverse gas chromatography data. The basic relationship used in this type of studies is " ... 

Abstract Inverse Gas Chromatography (IGC), in contrast to analytical chromatography, consists on adsorption of a known solute on an adsorbent whose properties are to be determined. The shape and positions of the peaks supply information about the nature and reactivity of the solid surface. If different probe molecules are used (i.e. polar and apolar molecules, molecules with acid/base properties), it is possible to study the specificity of these interactions. Therefore, IGC can be used both as a tool for both characterizing the adsorption of a given compound on a given solid or for studying the nature (in terms of acid-base properties, polar or apolar interactions, etc.) of the active sites of a certain catalyst. 

Inverse gas chromatography analysis at very high dilution and at finite concentrations of probe injection was carried out on a series of polymers and pigments used in paint formulations. Values of dispersion surface energies, and of acid-base interaction parameters were obtained for the materials, and pair interaction parameters were calculated from the results. The dispersion stability of each pigment/ polymer combination was measured and correlated with the acid-base interaction parameters of the materials, and is shown to justify the availability of fundamental thermodynamic interaction data to optimise performance aspects of protective coatings. 23 refs. 

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