(489b) Adsorption-Induced Deformation of Nanoporous Materials: From MMS to MOF

Phenomenon of adsorption-induced deformation attracted recently a considerable attention owing to its relevance to practical problems of mechanical stability and integrity of novel nanoporous materials. Micro- and mesoporous materials find numerous applications as selective adsorbents and catalysts, substrates for biosensors and drug delivery, membranes and films in various nanotechnologies, which involve fluids adsorbed or confined to nanoscale pores within rigid or compliant solid matrixes. Guest molecules adsorbed in pores cause a substantial stress in the host matrix leading to its contraction or swelling. Although various experimental manifestations of adsorption-induced deformation have been known for a long time, a rigorous theoretical description of this phenomenon is lacking. A general thermodynamic approach is suggested for predicting adsorption stress and respective deformation in various microporous and mesoporous materials. The proposed method is based on the analysis of adsorption isotherms by means of molecular simulations, density functional theory, and empirical models. The main focus is made on contraction-expansion cycles in microporous zeolites and active carbons [1, 2], and on hysteretic deformations in the course of capillary condensation and desorption in mesoporous molecular sieves (MMS) and structural transformations known as breathing transitions in metal-organic frameworks (MOF) [3].

[1] P.I. Ravikovitch and A.V. Neimark, - Density Functional Theory Model of Adsorption Deformation ? Langmuir, 2006, V.22, p.p. 10864-10868. [2] P. Kowalczyk, A. Ciach, and A.V. Neimark, - Adsorption-induced deformation of microporous carbons: pore size distribution effect, - Langmuir, 2008, V. 24, p.6603-6608. [3] A. V. Neimark, F.X. Coudert, A. Boutin, and A. H. Fuchs, - Stress-based model for the breathing of metal?organic frameworks, J. Physical Chemistry Letters, 2010, V.1, p.445?449.