Abstract
Branched forms of the archetypal polymer of intrinsic
microporosity
PIM-1 and the pyridinecarbonitrile-containing PIM-Py may be crosslinked
under ambient conditions by palladium(II) acetate. Branched PIM-1
can arise in polymerizations of 5,5′,6,6′-tetrahydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobisindane
with tetrafluoroterephthalonitrile conducted at a high set temperature
(160 °C) under conditions, such as high dilution, that lead to
a lower-temperature profile over the course of the reaction. Membranes
of PIM-1 and PIM-Py crosslinked with palladium acetate are sufficiently
stable in organic solvents for use in the recovery of toluene from
its mixture with dimethyl sulfoxide (DMSO) by pervaporation at 65
°C. With both PIM-1 and PIM-Py membranes, pervaporation gives
high toluene/DMSO separation factors (around 10 with a 77 vol % toluene
feed). Detailed analysis shows that the membranes themselves are slightly
selective for DMSO and it is the high driving force for toluene evaporation
that drives the separation.