Hydraulic Pressure-Programmed Molecular Transport in Tough Hydrogels.

Molecular transport through polymer networks, including hydrogels and biological matrices, underpins many applications ranging from water filtration and gas separation to drug delivery and cell culture. Conventional strategies for regulating transport in polymer networks primarily focus on tuning molecular diffusion through network mesh size and polymer chemistry, whereas convection is often considered negligible because nanoscale-mesh networks typically exhibit low fluid permeability. Although hydraulic pressure is a well-established driving force for convection in porous media, extending pressure-driven convection to non-porous polymer networks has remained fundamentally challenging because they can undergo substantial deformation or fracture under pressure gradients. Here, we demonstrate that hydraulic pressure applied across mechanically tough and grid-supported hydrogels enables robust and tunable solute transport while maintaining structural integrity. The characteristic transport time can be experimentally modulated by up to 65-fold, consistent with a coupled diffusion-convection model. Beyond tuning transport kinetics, applied pressure enhances size- and charge-dependent transport selectivity by up to 5.4-fold compared to pressure-free conditions. As a proof of concept, we demonstrate pressure-programmed antimicrobial delivery that dynamically controls doxorubicin transport while blocking bacterial penetration. These findings identify pressure-regulated convection as an underexplored mechanism for controlling transport in polymer networks.