Du, Chau My; (1995) The application of physicochemical descriptors to the characterisation of liquid and solid phases. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The understanding of polymer or solid sorbent interactions with gases is very important in probing properties of these materials. Partition, sorption and desorption are all essential here in assessing the potential usefulness of the liquid polymer and solid sorbents as potential protective, resisitant materials, gas sensors, and adsorbents. It would be of great advantage if the interaction behaviour between a gas and a polymer or solid phase can be quantified, so that suitable materials can be selected for specific functions. A method that was employed to measure polymeric or solid partition data at infinite dilution was inverse gas chromatography (IGC). Here the area of investigation is the stationary phase and not the solute or vapour as it would be in conventional chromatography. The work here is divided into sections; Gas-liquid chromatography—to measure the partition coefficients of gases on a polymer; Gas-solid chromatography—to measure the adsorption isotherms of gases on solid sorbents. The application of the general solvation energy relationship (LSER), equation (1), led to the evaluation of stationary phase sorption properties, and enabled the relative strengths of multiple simultaneous interactions, to be evaluated. Log SP = c + rR₂ + sπᴴ₂ + aΣαᴴ₂ + bΣβᴴ₂ + l logL¹⁶ (1) Here logSP is a set of gas-liquid chromatographic retention data for a series of gases on a given polymeric phase, or a series of gas-solid partition coefficients obtained at 298K. Using the method of multi linear regression analysis the values of the coefficients in equation 1 were obtained. These coefficients relate quantitatively to the properties of the polymer or adsorbent, that are complementary to the properties of the gaseous solutes. In addition, the solvatochromic method was used to measure physicochemical properties of the polymer. Here the interaction between a polymer film and an added dissolved dye was measured by the absorption of the films in the ultra violet-visible spectrometry. The two methods employed to characterise the properties of the polymer are compared and discussed.

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