Molecular reconstruction of bis(triethoxysilyl)ethane (BTESE)-derived membranes using simulated annealing algorithm

1,2-bis(triethoxysilyl)ethane (BTESE)-derived membranes are of great interest in gas-/liquid-phase separations, while the interplay between their chemical structure, pore topology, and permeability remains unexplored. This highlights the need for a realistic molecular model that captures the BTESE’s nanostructure and the complex transport within its pores. By considering the two important ingredients (atomic chemical composition and physical density), we first employ the simulated annealing procedure to reconstruct a database of the BTESE models of different densities. By comparing the X-ray diffraction pattern with the experimental data, the reactive force field used in our molecular simulations strategy is found to capture the amorphous nature of the BTESE’s nanostructure. In particular, the molecular texture parameters are screened to match the experimental density. We then turn to extract our BTESE models using the radial distribution function, bond order, and atomic partial charge. The chemical bonding features show that our BTESE model consists of the carbon–silicon–oxygen backbone with a few small molecules formed. Moreover, the pore size distribution of our BTESE model is found to be in good agreement with the experimental data. The sieving effect of the pore topology on the gas permanence observed in experiments is found to be well explained by such a molecular picture. These findings for the realistic molecular model and pore topology provide a means to probe the relationship between chemical structure and the gas transport within pores of the BTESE-derived membranes, as well as other organosilica membranes.