The surface properties of cellulose and lignocellulosic materials assessed by inverse gas chromatography: a review

Abstract

The physicochemical surface properties of cellulose and lignocellulosic materials are of major importance in the context of the production of composites, in papermaking, and textile area. These properties can be evaluated by using inverse gas chromatography (IGC), a particularly suitable technique for the characterization of the surface properties of fibrous materials and powders. At infinite dilution conditions of appropriate gas probes, IGC may provide important parameters including the dispersive component of the surface energy of the material under analysis, thermodynamic data on the adsorption of specific probes, and Lewis acid-base interaction parameters between the matrix and the filler of composite materials. This paper critically reviews the most relevant results available in the literature concerning the characterization of cellulose and lignocellulosic materials using IGC. Emphasis will be put into the cellulose and nanocellulose surface properties, changes in the surface properties of cellulose and lignocellulosic materials after chemical and physical modifications, and in the compatibility of cellulose-based materials with polymeric matrices. The surface properties of non-woody fibers will also be considered. Before discussing the results available in the literature, the theoretical background and the main approaches used for the calculation of parameters accessed by IGC will be given. It is expected that this review can contribute to a better knowledge of the physicochemical surface properties of cellulosics.

Surface properties of distinct nanofibrillated celluloses assessed by inverse gas chromatography

“…The substitution of a few hydroxyl groups for carboxylate groups (COO -Na + ) in the TEMPO NFCs would generate, in principle, a reduction of the Lewis acidity and an increase of the Lewis basicity of the material because hydroxyl is mainly an electron acceptor (acidic) group while COO -is mainly an electron donor (basic) group. In fact, the TEMPO NFCs showed lower specific affinities with THF (basic probe) and with acetone and ETA (amphoteric probes with more Lewis basic than Lewis acidic character [11][12]) than the enzymatic nanocellulose. However, the affinity with an acidic probe such as TCM was not higher for the TEMPO NFCs.…”

“…It enables to obtain the dispersion component of the surface energy, adsorption thermodynamic parameters with a wide range of polar substances (specific components of the free energy of adsorption, enthalpy and entropy of adsorption), Lewis acidbase character of the surface, surface nanoroughness parameter, etc. [11][12][13][14]. Thus, using IGC a cellulosic fibrous material can be thoroughly characterized with respect to its surface chemical properties.…”

“…Two columns were prepared for each material with the final results being the average of two separate measurement series. The theoretical aspects of inverse gas chromatography have been previously described [11][12][13]. Using this technique, the dispersion component of the surface energy, and the specific components of the work of adhesion, enthalpy and entropy of adsorption of polar probes on the surface of the analysed materials were obtained.…”

“…Using this technique, the dispersion component of the surface energy, and the specific components of the work of adhesion, enthalpy and entropy of adsorption of polar probes on the surface of the analysed materials were obtained. The values of the molecular surface area (a) and dispersion component of the surface energy ( l d ) of the probes used for the IGC analysis can be found elsewhere [11][12].…”

Surface properties of xylan and xylan derivatives measured by inverse gas chromatography

“…Inverse gas chromatography (IGC) is an appropriate tool to assess the surface properties of powdered solid materials, such as xylans, not possible to assess adequately, for instance, by classical contact-angle measurements (due to associated problems like porosity, roughness, surface heterogeneity). IGC enables to obtain the dispersive component of the surface energy, specific interactions (non-dispersive) with polar probes, Lewis acid-base character of the surface, surface nanoroughness parameter, Flory-Huggins interaction parameter [22][23][24][25], among other properties. This technique has been widely used for the study of cellulose and lignocellulosic materials U N C O R R E C T E D P R O O F [22] but, to our knowledge, it has never been reported before for the study of xylans of any type.…”