Determination of the elastic modulus of mesoporous silica thin films by x-ray reflectivity via the capillary condensation of water

Abstract

The mechanical properties of mesoporous silica films were characterized by x-ray reflectivity measurements. The measurements provide information on the deformation of the pores and the walls induced by the adsorption of water in the pores. The analysis of the nanoscaled deformations supplies a method to determine the elastic modulus E of thin porous films. The nanodeformation of the porous network during its filling with water is interpreted in three regimes of isotherm sorptions.

Adsorption-induced deformation of nanoporous materials—A review

“…25. Another study on the determination of elastic properties of thin solid films was presented by Dourdain et al 29 Unfortunately, the authors did A different way to use adsorption-induced deformation for materials characterization was proposed by Ustinov and Do. 93 Based on their theoretically predicted strain isotherms, which were very strongly pore-size dependent, they suggested that from experimentally measured strains one can extract information about the pore size distribution (PSD).…”

“…However, in order to give the theory a full predictive capability, it is necessary to have an expression for this so-called pore load modulus 65 as a function of the underlying physical parameters, in particular, the elastic properties of the solid matrix and the pore structure (volume fraction, size, and shape of the pores). This is of utmost importance when the adsorption strain data is used specifically for an estimation of elastic properties of a material, 23,25,29 as discussed further in Section IV B.…”

“…Dourdain et al used in situ X-ray reflectivity to measure the strain isotherms for water adsorption on mesoporous silica films and suggested to use these measurements for deriving the elastic properties of thin films. 29 To our knowledge, in situ X-ray scattering techniques applied to the adsorption/deformation behavior have not been performed on porous carbonaceous systems. Recently, however, in situ small angle neutron scattering was employed to measure the adsorption-induced deformation of microporous carbons.…”

Elastic response of mesoporous silicon to capillary pressures in the pores

“…This pressure causes deformation of the pore, and as a result deformation of the porous material as a whole. This effect, known as adsorption-induced deformation has been experimentally observed for various mesoporous materials: Vycor glass [18,19], templated silica [20][21][22], low-k films [23,24], aerogels [25,26], porous gold [27] and pSi [28]. There are two ways to * ggor@princeton.edu measure the adsorption strains experimentally: for materials which can be prepared as macroscopic samples, the dilatometric technique can be used, and the reported strain is the relative change of the length of the sample [18,19,25,27].…”

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

“…3,4 The major focus of most previous works has been limited to the elastic response of porous samples to external mechanical loads and the related properties including the effective bulk and Young's moduli. [6][7][8] However, the elastic response of porous materials to internal pressure loadings has attracted much less attention. 9 There are numerous application examples of porous materials, especially for pores in nanoscale subjecting to internal loading, such as gas or fluid adsorption in nanoporous solids in the fields of geology, biology, chemistry, etc.…”