Deformation dynamics of nanopores upon water imbibition

• 成果类型: Article
• 署名作者: Sanchez, Juan; Dammann, Lars; Gallardo, Laura; Li, Zhuoqing; Froeba, Michael; Meissner, Robert H.; Stone, Howard A.; Huber, Patrick
• 署名单位: Hamburg University of Technology; Helmholtz Association; Deutsches Elektronen-Synchrotron (DESY); Hamburg University of Technology; University of Hamburg; University of Hamburg; Helmholtz Association; Helmholtz-Zentrum Hereon; Princeton University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12067
• DOI: 10.1073/pnas.2318386121
• 发表日期: 2024-09-17
• 关键词: adsorption-induced deformation; small-angle scattering; capillary condensation; amorphous silica; simulations; sorption; glass; expansion; SURFACES; charcoal

摘要

Capillarity-driven transport in nanoporous solids is widespread in nature and crucial for modern liquid-infused engineering materials. During imbibition, curved menisci driven by high negative Laplace pressures exert an enormous contractile load on porous matrix. Due to the challenge of simultaneously monitoring imbibition and deformation with high spatial resolution, the resulting coupling of solid elasticity liquid capillarity has remained largely unexplored. Here, we study water imbibition mesoporous silica using optical imaging, gravimetry, and high-resolution dilatometry. In contrast to an expected Laplace pressure-induced contraction, we find a square root-of-time expansion and an additional abrupt length increase when the menisci reach the top surface. The final expansion is absent when we stop the imbibition front inside the porous medium in a dynamic imbibition-evaporation equilibrium, as typical for transpiration-driven hydraulic transport in plants, especially in trees. These peculiar deformation behaviors are validated by single-nanopore molecular dynamics simulations and described by a continuum model that highlights the importance expansive surface stresses at the pore walls (Bangham effect) and the buildup or release of contractile Laplace pressures as menisci collectively advance, arrest, or disappear. Our model suggests that these observations apply to any imbibition process in nanopores, regardless of the liquid/solid combination, and that the Laplace contribution upon imbibition is precisely half that of vapor sorption, due to the linear pressure drop associated with viscous flow. Thus, simple deformation measurements can be used quantify surface stresses and Laplace pressures or transport in a wide variety of natural and artificial porous media.