MOF/Hydrophobic Polymer Composites for Toluene Capture

We present a comprehensive computational study of DUT-4(Al)-based composites incorporating hydrophobic polymers, polystyrene (PS), polypropylene (PP), poly(vinylidene fluoride) (PVDF), and polydimethylsiloxane (PDMS), to evaluate their potential for selective toluene capture under humidity. Using a multiscale approach combining density functional theory (DFT), grand canonical Monte Carlo (GCMC), molecular dynamics (MD) simulations, and graph theory tools, we establish structure-property relationships linking polymer infiltration behavior to MOF porosity, toluene sorption capacity, and transport. Our results reveal a clear hierarchy of polymer penetration within DUT-4(Al), ranging from strong channel disruption in PP to largely surface-confined PS, with PVDF and PDMS exhibiting intermediate infiltration while preserving continuous pore pathways in the MOF channels. These structural differences directly govern adsorption performance, with DUT-4(Al)/PS retaining the highest relative toluene uptake and DUT-4(Al)/PP the lowest. Among the composites studied, DUT-4(Al)/PVDF emerges as the most balanced system, combining substantial toluene accessibility with favorable dynamics. Importantly, MD simulations show that PVDF promotes rapid toluene diffusion into MOF channels while effectively hindering water penetration, thereby enhancing selective uptake under humid conditions. Overall, this work demonstrates that rational polymer selection is a powerful strategy to tune adsorption and transport properties in MOF/polymer composites. The insights provided here establish a general computational framework for the design of robust, humidity-resistant composites for VOC capture applications.