Inverse gas chromatography and acid-base

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... 

Acid-base properties of oxide surfaces are employed in many fields and their relationship with PZC has been often invoked. Adsorption and displacement of different organic molecules from gas phase was proposed as a tool to characterize acid-base properties of dry ZnO and MgO [341]. Hammet acidity functions were used as a measure of acid-base strength of oxides and some salts [342]. Acidity and basicity were determined by titration with 1-butylamine and trichloroacetic acid in benzene using indicators of different pAg. There is no simple correlation between these results and the PZC. Acid-base properties of surfaces have been derived from IR spectra of vapors of probe acids or bases, e.g. pyridine [343] adsorbed on these surfaces. The correlation between Gibbs energy of adsorption of organic solvents on oxides calculated from results obtained by means of inverse gas chromatography and the acceptor and donor ability of these solvents was too poor to use this method to characterize the donor-acceptor properties of the solids [344],... 

INVESTIGATION OF THE ACID-BASE PROPERTIES OF AN MCM-SUPPORTED RUTHENIUM OXIDE CATALYST BY INVERSE GAS CHROMATOGRAPHY AND DYNAMIC GRAVIMETRIC VAPOUR SORPTION... 

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. 

Lately the most frequently used technique for the determination of thermodynamic and acid/base characteristics is inverse gas chromatography [30,73-75]. In IGC the unknown filler or fiber surface is characterized by compounds, usually solvents, of known properties. IGC measurements can be carried out in two different ways. In the most often applied linear, or ideal, IGC infinite concentrations of n-alkane are injected into the column containing the filler to be characterized. The net retention volume (V ) can be calculated by ... 

Ohta M, Buckton G. 2004. The use of inverse gas chromatography to asess the acid-base contributions to surface energies of cefditoren pivoxil and methacrylate copolymers and possible links to instability. Int. J. Pharm. 272 121-128. 

Uhlmann P, Schneider S. 2002. Acid-base and eurface energy characterization of grafted polyethylene using inverse gas chromatography. J. Chromatogr. A 969 73-80. 

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. 

Whereas conventional chromatographic methods manipulate the surface energetics of sorbents to separate fluid mixtures, inverse gas chromatography uses known properties of fluids to characterize surface properties of solids. Specifically, Lewis acids and bases are used, in this study, as probes to deduce the nature and extent of solid/gas attraction from the shape of chromatograms, which are transformed adsorption isotherms. IGC can determine the specific surface (m2/g) of the substrate, whether the surface is acidic, basic, amphoteric, or neutral, and whether the surface is homogeneous or heterogeneous. 

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 (IGC) was applied to E-glass fiber surfaces modified by various silane coupling agents. Using homologous series of alcohol (acid) and amine (base) vapor... 

Inverse gas chromatography in the examination of acid base and some other properties of solid materials... 

Hamieh, T., FadlaUah, M.B., and Schultz, J., New approach to characterize physicochemical properties of solid substrates by inverse gas chromatography at infinite dilution, lit. Determination of the acid-base properties of some solid substrates (polymer, oxides and carbon fibres) A new model. J. Chromatogr. A. 969, 37, 2002. 

Dynamic vapour phase techniques are interesting tools for the determination of these properties. When compared to standard wettability experiments, they provide two main benefits. They can easily and reproducibly be applied to powders and a wide variety of probe molecules can be selected. In the current study dynamic gravimetric vapour sorption (DVS) and inverse gas chromatography (IGC) have been used to characterise the energetic and acid-base properties of a calcined ruthenium oxide / MCM41 catalyst as well as the corresponding MCM41 support. 

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. 

Inverse gas chromatography (IGC) is a rapid and reliable method used to evaluate the acid-base character of activated carbon surfaces. This method employs physical adsorption of appropriate molecnlar probes in a chromatographic (dynamic) experiment [288]. The amounts of solutes injected are very small, and it is assumed that the adsorption is described by Henry s law. From the retention volume the free energy of adsorption, AG°, is calcnlated as follows ... 

There is a plethora of analytical techniques available to assess the acid-base properties of materials. They range from wettability and chromatographic measurements to spectroscopic approaches and more sophisticated scanning probe microscopic methods [12,13,15-19,59-61]. For the purpose of this contribution, the focus will be on contact angle measurements, inverse gas chromatography, x-ray photoelectron spectroscopy, and atomic force microscopy. 

Inverse gas chromatography (IGC) is a method very well used by the adhesion community for obtaining thermodynamic and morphological information on a variety of materials such as fillers, pigments, colloids, fibers, powder, wood, and polymers [17,60,61,85-94]. The term inverse means that the stationary phase is of interest by contrast to conventional gas chromatography in which the mobile phase is of interest. Its success lies in the fact that it is simple, versatile, usable over a very wide range of temperature, and very low cost. IGC has a well established background for the assessment of yg acid-base parameters for polymers and fillers. Such thermodynamic parameters can be further used to estimate the reversible work of adhesion at polymer-fiber and polymer-filler interfaces [95,96],... 

Berg, J. C. and Pearson, S. W., The acid-base characterization of cellulosic fibers using inverse gas-chromatography, Abstr. Papers Am. Chem. Soc., 203, 256-COLL (1992). 

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] ... 

Belgacem, M.N. Gandini, A. Inverse Gas Chromatography as a Tool to Characterize Dispersive and Acid-Base Properties of the Surface of Fibers and Powders— Surfactant Science Series—VoL 80 Pefferkom, E., Ed. Marcel Dekker, Inc. New York, 1999,41-124. 

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. 

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