Inverse Gas Chromatography in Analysis of Polymers

Abstract

This article describes the application of inverse gas chromatography (IGC) to the study of synthetic and natural polymers. The word “inverse” is used to indicate that the component of interest is the stationary phase, either as a finely divided powder or coating, dispersed on a suitable inert support and packed into a chromatographic column. The time required for a probe molecule to pass through the column gives a measure of the molecular interactions between the probe and the polymer which can be quantified with the help of chromatographic theory. Historically, most thermodynamic studies on polymers were carried out in dilute solution, but IGC provides information on condensed phases under conditions much more similar to those under which polymers are actually used. Using this technique, melting, glass and other solid‐phase transitions can be studied and quantified. Degrees of crystallinity can be determined in an unambiguous procedure without calibration by other methods. Solubility, permeability and diffusion constants can be determined for probe molecules. IGC is also used extensively in determining the permeability of additives such as antioxidants in polymers, as well as thermodynamic quantities such as activity coefficients, heats of solution, Flory–Huggins interaction parameters (χ), and solubility parameters. Surface areas can be measured at any desired temperature by the determination of the adsorption isotherms of suitable probes. Measurements on polymer blends can yield important information on polymer–polymer interactions and can be used to predict the compatibility of the components over a wide range of temperatures. The use of finite concentration IGC provides a rapid method of determining the density of crosslinks in rubber‐like polymers. Almost any commercial gas chromatograph can be easily modified to carry out IGC experiments by procedures described in this report. The method provides a wealth of information of both fundamental and practical importance in the study of polymeric materials.

Investigation of Polymers by Inverse Gas Chromatography

“…Now IGC is a reliable source of information on absorption and adsorption in polymers and on polymer properties. Numerous reviews and several books have been written on IGC. − Some of them were published 20–40 years ago. − Though being brilliant or simply useful, today they are rather outdated. In the 21st century researchers returned many times to the subjects of IGC. − A special book was published dealing with general questions of IGC.…”

“…Numerous reviews and several books have been written on IGC. − Some of them were published 20–40 years ago. − Though being brilliant or simply useful, today they are rather outdated. In the 21st century researchers returned many times to the subjects of IGC. − A special book was published dealing with general questions of IGC. It should be noted that most of those reviews focused on such subjects as polymer surface studies and polymer blends, ,,, determination of T g and other properties of polymers, , investigation of surfactants, pharmaceuticals, and fibers. , Meanwhile, some important issues did not receive proper attention in the existing literature, for example, thermodynamics of glassy polymers, IGC as a probe method for investigation of free volume in polymers, and some others.…”

“…It was included into official recommendations of IUPAC and is still employed in the current works (see e.g. ref ). However, later it was noted − that this procedure is not justified.…”

Interactions of Solvents with Low Molar Mass and Side Chain Polymer Liquid Crystals Measured by Inverse Gas Chromatography

“…Inverse gas chromatography, IGC, has been used to investigate the physicochemical properties of a wide range of systems including polymers. , While it is a dynamic method, it was shown some years ago that measurements recorded under the correct conditions could give accurate equilibrium thermodynamic information. , The retention of a solvent or “probe” molecule in the material is recorded, and the measurement made effectively at infinite dilution of the probe. A range of thermodynamic parameters can then be calculated.…”

Solubility and diffusivity of solvents and nonsolvents in poly(methyl methacrylate co butyl methacrylate)

“…Ω ∞ 1 gives an idea of the polymer-solvent compatibility indicating that; Ω ∞ 1 < 5 good solvents; 5 < Ω ∞ 1 < 10 moderate solvents; Ω ∞ 1 > 10 bad solvents [16]. The Flory-Huggins interaction parameter (χ ∞ 12 ), which was used as a measure of the strength of interaction, and therefore as a guide in the prediction of polymer solvent compatibility is related to the weight fraction activity coefficient by the following equation [17]:…”