Atomistic insights into interfacial failure prevention of clay- polyurethane composites

YS Wu and C Zhang and CX Wang and HY Fang, COMPUTERS AND GEOTECHNICS, 187, 107484 (2025).

DOI: 10.1016/j.compgeo.2025.107484

Non-aqueous reactive foamed polyurethane (PU) grouting materials form impermeable composite structures by infiltrating the pore networks of clay. The durability of these composites critically depends on water microstructures and transport behaviors in within both clay and clay-PU hybrid nanochannels, which are remain unclear due to experimental scale limitations. Here, molecular dynamics simulations were employed to investigate the structural and dynamic properties of water confined in montmorillonite (MMT) and MMT-PU nanochannels. The results show that MMT walls induce a 2-nm-thick dense adsorption layer stabilized by high- density hydrogen bonds networks, whereas hydrophobic PU walls generate only slight adsorbed layers in extremely narrow channels (<2 nm). Hydrophobic walls amplify structural disorder and confinement effects, resulting in higher initial flow pressures and larger critical channel sizes required for water transport in MMT-PU nanochannels compared to MMT nanochannels. Channel expansion reduces confinement, but hydrophobic walls slow this attenuates process. Water pressure, channel size, and wettability collectively regulate flow regimes by redistributing molecular forces. In MMT nanochannels, symmetric Poiseuille-to-plug transitions dominate under increasing pressure and channel size. In contrast, asymmetric plug flow persists in MMT-PU nanochannels, with a 1.5-nm-thick boundary layer near PU walls. These findings provide atomistic insights into optimizing PU grouting materials for geotechnical engineering applications, particularly in mitigating interfacial failure through nanoscale channel design and wettability control.

Return to Publications page