Transferable molecular model for benzimidazole-linked polymer membranes applied in hydrogen separation

Benzimidazole-linked polymers (BILPs), with their densely cross-linked ultramicroporous networks, are promising for hydrogen separation. However, the molecular selectivity mechanisms remain poorly understood, hindering rational design. We present a multiscale simulation for BILPs, using BILP-101 as a model, to precisely resolve its microstructural features and elucidate H 2 separation performance at an unprecedented molecular level. Through meticulous optimization of simulation protocols, including force fields, atomic charges, chain configurations, and equilibration cycles, optimal simulation protocols were identified, and the interplay of pore architecture and chemical interactions driving H 2 selectivity was uncovered. Our simulations not only demonstrate precise control over pore geometry but also accurately replicate experimental H 2 /CO 2 , H 2 /N 2 , H 2 /CH 4 separation performance across standard and elevated temperatures. The generality of our model was further validated by its strong agreement with empirical data for BILP-5 and BILP-15. This work bridges advanced molecular modeling with experimental validation, providing design principles to accelerate the development of next-generation BILPs or other polymer membranes for energy-efficient gas separation.