Abstract
Polymer of intrinsic microporosity (PIM-1) was prepared according to a new procedure – precipitation polycondensation in DMSO solution. The permeability coefficients were determined in the “as cast” and ethanol treated samples of this material. It was shown that permeability of the novel polymer is higher than that of PIM-1 samples prepared according to the traditional methods, while selectivity was lower. Free volume in the novel PIM-1 was studied using the PALS technique. Positron life time parameters and the radii of free volume elements were virtually the same as in PIM-1 samples investigated earlier. The samples of novel PIM-1 were subjected to treatment by supercritical CO2 and annealing of free films and films in strained state. The treatment with scCO2 leads qualitatively to the same results as insertion of the films into EtOH (increase in gas permeability) although the observed Pi values are somewhat lower. Annealing of the films in strained and free state causes significant decrease in gas permeability with respect to all the gases but increase in selectivity. This effect is rather strong, so some the data points are even located above the Upper Bound 2008 in Robeson diagrams. Aging of PIM-1 samples for 30–60 days was also studied, and its mechanism is considered.
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