Swelling of poly(methyl methacrylate) and poly(butyl methacrylate) samples in supercritical carbon dioxide and propagation of diffusion fronts in the samples were studied in situ at various temperatures and pressures using direct optical observation. The difference in the appearance of diffusion fronts in these polymers with different glass transition temperatures was observed. The diffusion coefficients of carbon dioxide molecules in the polymers were determined both from swelling kinetics and from motion of diffusion fronts. A good agreement between these two values was found. The dependences of the diffusion coefficients and equilibrium swelling degrees of the polymers on pressure and temperature of supercritical carbon dioxide during sample exposure were determined and discussed.

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Promising new technique of polymer deposition from solutions in supercritical carbon dioxide (sc CO2) has been applied to form ultrathin Teflon AF2400 copolymer films on substrates with different properties. Atomic force microscopy study of the coatings morphology has been performed for the first time and has revealed surprisingly high film uniformity, very low roughness, and good stability during the scanning procedure. Our findings have demonstrated the intriguing possibilities of the applied film-forming process allowing to deposit the thin-film coatings and also individual macromolecules in a controllable manner. This is because the variations of solution temperature and pressure influence significantly the dissolving power of sc CO2; therefore, the macromolecule precipitation depends strongly on the thermodynamic regime and can be easily controlled. The influence of substrate properties, exposure conditions, and deposition kinetics on the film morphology, thickness, and level of surface coverage has been shown.