Imbibition- and Drying-Induced Deformation of Nanoporous Solids

We present time-dependent macroscopic dilatometry experiments on the deformation of nanoporous monoliths (Vycor glass) upon spontaneous, capillarity-driven infiltration of water as well as drying. We find two distinct dynamical regimes. One of them can be quantitatively traced to deformation originating in changes in the surface stress at the inner pore walls (dynamic Bangham’s regime), whereas the second results from Laplace pressure effects. The interplay of both strain-inducing regimes allows to infer the water content in the pore space. 

The theoretical framework used to describe our experimental data combines simple continuum mechanics and fluid dynamics on the macroscopic porous-solid scale, supported by molecular dynamics simulations on the single-nanopore scale. Our study demonstrates that it is possible to monitor imbibition and drying dynamics by simple dilatometry measurements, offering multiple potential applications.