Robeson plots for (a) O2/N2, (b) CO2/N2, (c) CO2/CH4, and (d) H2/N2 gas pairs showing the data for PIMs. The black and red lines represent the 1991 and 2008 upper bounds, respectively. References for notable data points are given in square brackets. Data for methanol treated films of PIM-1 are given as green squares whereas the data for a methanol treated film of spirobisfluorene-based PIM, prepared from monomer A18, is given as a red square.Data for other PIMs are given as black triangles and for PIM polyimides as black circles.
