Quantitative characterization of the acid-base properties of solvents, polymers, and inorganic surfaces

Abstract

The growing realization of the importance of intermolecular acid-base interactions in promoting the solubility, adsorption, and adhesion of polymers to other materials has caused a demand for the quantitative characterization of the acid-base properties of the commonly used solvents, polymers, and inorganic fillers and substrates. There have been several recent advances in the measurement techniques for such determinations, especially in the fields of inverse gas chromatography, microcalorimetry, ellipsometry, FTIR, NMR, and XPS spectroscopy, all leading to the capability of determining the Drago E and C constants or the Gutmann acceptor numbers (AN) or donor numbers (DN) for the acidic or basic sites of solvents, polymers, or inorganic surfaces. In the last year, new studies have also allowed the characterization of the specific acid-base cohesive interactions in solvents and polymers, and the determination, from contact angle measurements on polymers, of the surface concentration and strength of acidic and basic surface sites. All of these techniques are discussed in this paper and it is expected that they will soon become standard laboratory practices.