The pore-load modulus of ordered nanoporous materials with surface effects

Abstract

Gas and liquid adsorption-induced deformation of ordered porous materials is an important physical phenomenon with a wide range of applications. In general, the deformation can be characterized by the pore-load modulus and, when the pore size reduces to nanoscale, it is affected by surface effects and shows prominent size-dependent features. In this Letter, the influence of surface effects on the elastic properties of ordered nanoporous materials with internal pressure is accounted for in a single pore model. A porosity and surface elastic constants dependent closed form solution for the size dependent pore-load modulus is obtained and verified by finite element simulations and available experimental results. In addition, it is found to depend on the geometrical arrangement of pores. This study provides an efficient tool to analyze the surface effects on the elastic response of ordered nanoporous materials.

Adsorption-induced deformation of nanoporous materials—A review

“…46 The two-dimensional model for the pore load modulus 41 presented above has recently been generalized to take into account additional surface elastic constants. 124 Such additional constants could be introduced for nanoscale solids, where elastic properties can deviate from their bulk values. However, for mesoporous materials, where the characteristic pore size and pore wall thickness are of the order of several nanometers, these deviations are likely to be negligible.…”

Using capillary forces to determine the elastic properties of mesoporous materials

“…Since these walls are only a few nanometers thick, one expects that their effective modulus can be quite different from that of the bulk, similarly to a single nanowire [17] or nanocantilever [18]. The relevance of finite-size effects for mesoporous materials has been recently discussed [19,20], but experimental data are scarce. For mesoporous silica, the wall material (chemical composition, microstructure) depends on the synthesis, so that changes in modulus are difficult to interpret.…”

Elastic Compliance and Stiffness Matrix of the FCC Lennard-Jones Thin Films: Influence of Thickness and Temperature

“…Conversely, the deformation of a saturated nanoporous medium along the main desorption curve is also a powerful tool to measure the elastic constants of nanometric systems, in complement to direct measurements. [20][21][22][23][24][25][26][27][28][29][30][31][32] The knowledge of the fluid-solid interactions has also proven to be important due to specific effects. 33 Understanding the mechanical properties of nanosystems is also important in the context of nanoporous solids, in particular regarding the adsorption/desorption hysteresis that appears for a sufficiently low temperature.…”