(483b) Adsorption-Induced Surface Stresses Based on Electronic Structure DFT Calculations

All porous materials deform during fluid adsorption. Although for most of the materials the experimentally observed strains are small, this phenomenon has a number of important applications, including sensors [1], actuators [2], CO2 sequestration [3]. In addition to those, adsorption-induced deformation has potential for characterization of porous materials because deformation is very sensitive to the pore sizes. In recent years there has been a major progress in developing theory of adsorption-induced deformation [4-6]. However, these studies were focused on calculating the pressure in the fluid phase, while the stresses in the solid phase were not considered explicitly. The current work fills this gap, presenting the electronic-structure density functional theory modeling of the dry and wet silica surfaces. In addition to the information on change of the surface energy with fluid adsorption, our calculations show how the components of surface stress tensor change. This change is the key parameter necessary for quantitative understanding of the adsorption-induced deformation phenomenon.

1. Baimpos, T.; Gora, L.; Nikolakis, V. & Kouzoudis, D. Selective detection of hazardous VOCs using zeolite/Metglas composite sensors Sensors and Actuators A: Physical, 2012, 186, 21-31

2. Bertinetti, L.; Fischer, F. & Fratzl, P. Physicochemical basis for water-actuated movement and stress generation in nonliving plant tissues Physical Review Letters, 2013, 111, 238001

3. Brochard, L.; Vandamme, M.; Pellenq, R. J.-M. & Fen-Chong, T. Adsorption-induced deformation of microporous materials: coal swelling induced by CO2-CH4 competitive adsorption Langmuir, 2012, 28, 2659-2670

4. Ustinov, E.; Do, D. Effect of adsorption deformation on thermodynamic characteristics of a fluid in slit pores at sub-critical conditions. Carbon 2006, 44, 2652−2663.

5. Gor, G. Y.; Neimark, A. V. Adsorption-induced deformation of mesoporous solids: Macroscopic approach and density functional theory. Langmuir 2011, 27, 6926−6931.

6. Long, Y.; Palmer, J. C.; Coasne, B.; Sliwinska-Bartkowiak, M.; Jackson, G.; Müller, E. A. & Gubbins, K. E. On the molecular origin of high-pressure effects in nanoconfinement: The role of surface chemistry and roughness J. Chem. Phys., 2013, 139, 144701