Capillary column inverse gas chromatography (CCIGC) is a powerful tool to determine solubility and diffusion for a variety of polymer-solvent systems. The goal of this work was to determine solubility and diffusion of a toluene-polystyrene/polyethylene copolymer system in a temperature range starting well above the glass transition temperature T_g of the copolymer down to below the T_g of the copolymer. These suited two purposes: (1) partition coefficients as a function of polymer film thickness can be used to show the contribution of adsorption to the retention mechanism below the T_g and (2) the data can be used to determine the polymer's T_g.

Three open tubular capillary columns were coated with the polystyrene-polyethylene copolymer, applying film thicknesses of 2.0, 3.4, and 6.0 micrometers, and measurements in the temperature range of 100 to -10°C were conducted. A plot of resulting partition coefficients, K, as a function of reciprocal temperature, showed the classical S-shape. Some variation of the partition coefficients with film thickness was observed. This was attributed to the simultaneous occurrence of several mechanisms, such as adsorption and absorption below the T_g.

Van't Hoff plots based on first moment and maximum retention time were S-shaped and indicated an approximate T_g of 10°C. A plot of moment-ratio as a function of reciprocal temperature showed an abrupt change of slope at 25°C. Diffusion coefficients as a function of reciprocal temperature were fitted through free volume parameters above T_g. Below the T_g, the D_p values diverged from the expected behavior.