The perm-selectivity is plotted with respect to perme-ability on a log-log scale in Fig. . Fig. reports again the experimental results obtained from the literature with the PIM based membranes highlighted in black, and panel (b)-(d) demonstrates the results for C 1 -C 3 , respectively. In order to emphasize the trend, percolated matrices with higher fractions of solid lattice sites have also been incorporated into the analysis. Concentrating on the predictions from the theory, all systems considered here exhibit a similar trend where the performance cloud can be essentially divided into two regions. The first region, on the left side of each graph, is associated with low porosity structures. In this region, the systems exhibit a significant degree of scattering. However, by moving to the matrices with higher porosities, the permeability of the structure in this regime can be increased without significant sacrifice of perm-selectivity. This process continues up to a region in permeability (or density of the structure) beyond which there is a sharp decrease in perm-selectivity. This sharp decrease constitutes the second region.