We construct the polymeric membrane models via the multi-step crosslinking of binary For solubility calculations, MD simulations are performed with a time step of 1.0 fs in the following sequence: (1) energy minimization, (2) 0.5 ns NVT-MD simulation at 600 K, (3) 0.5 ns NPT-MD simulation at 600K and 1 bar, (4) 5 thermal annealing cycles from 600 to 300K with a temperature interval of 50K at 1 bar, (5) 0.5 ns NPT-MD simulation at 300K and 1 bar, and (6) 0.5ns NVT-MD simulation at 300K. Finally, the solubility coefficients of relevant gases are evaluated at infinite dilution, which are equal to their Henry's constants .