Quantum effects of hydrogen storage in ϵ and δ semicrystalline phases of syndiotactic polystyrene through adsorption

AbstractSyndiotactic polystyrene (sPS) is a stereoregular semicrystalline polymer which presents complex polymorphic behaviour and has been explored as an alternative for hydrogen storage using adsorption. The methodology of gas retention using a light and cheap porous material offers many advantages. To establish the adsorption capacity of a specific material, adsorption isotherms are generally measured. However, to gain a better understanding of the underlying phenomena occurring at a nanoscale level (e.g. confined interactions of H2 in sPS) and, moreover, as a predictive tool, alternative methods such as molecular simulations are required. In this work, we present Grand Canonical Monte Carlo simulation results for hydrogen (H2) adsorption isotherms of δ and ϵ phases of sPS. H2 molecule was described as a 1-site model with Lennard-Jones and Exp-6 potentials, within the Wigner–Kirkwood mean-field approximation to introduce quantum corrections. Both polymer phases were modelled using an atomistic force field and the initial configurations were relaxed using molecular dynamics for temperatures T=45K, 60K and 77K. Adsorption isotherms for each system were obtained for both classical and semiclassical potentials. Additionally, adsorption isotherms for both phases were compared with experimental adsorption data at 77K from previous work.Keywords: Hydrogenadsorption isothermsMonte Carlomolecular dynamicsWigner–Kirkwood theory Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingWe acknowledge support from the University of Guanajuato, Dirección de Investigación y Posgrado (grant CIIC 151/2022 and 250/2023). Also, we gratefully acknowledge the computing time granted by LANCAD/CONACyT on the supercomputer Miztli at DGTIC UNAM. We thank CONACyT for Kevin R. Arriola Gonzalez's PhD scholarship, number 819666.