Predicting Structure and Transport in Disordered Mesoporous Materials via Cooperative Phase Transitions.

The interplay between material structure, thermodynamics, and transport of confined fluids in nanoporous solids underpins their practical applications. Mesoporous networks embedded within microporous frameworks of zeolites and MOF materials are attracting increasing attention as they can enhance material properties and boost their performance. Correlating the mesoporous network structure with transport properties, however, remains challenging due to an apparent conflict: most thermodynamic models focus on single-pore equilibrium behavior, whereas transport is largely dictated by the organization of the pore network. Herein, we show that exploiting cooperative phenomena in gas adsorption governed by structural disorder resolves this challenge. We present a unified framework that links the structure, thermodynamics, and transport by leveraging recent advances in the statistical thermodynamic description of nonequilibrium-phase states arising from cooperativity across pore networks. Structural descriptors of the mesopore space, extractable from gas sorption measurements including, beyond conventional pore size distributions, the average pore connectivity and a hierarchy factor describing deviations from a fully random structure, are used to accurately predict diffusive transport. The framework's robustness is validated for mesoporous materials with both homogeneous and hierarchical pore architectures through experiments using transmission electron microscopy (TEM), mercury intrusion, and pulsed-field gradient (PFG) NMR.