Properties of liquid acetone in silica pores: Molecular dynamics simulation

• Published in: The Journal of chemical physics 1996-04, Vol.104 (16), p.6319-6326
• Main Authors: Bródka, A., Zerda, T. W.
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.471292

Molecular dynamics simulations are reported for molecular acetone confined in a model cylindrical pore within a structure representing amorphous silica. Calculations are performed for pores of average diameters 1.5, 2.0, 2.5, and 3.0 nm. To evaluate the role of electrostatic interactions on the structure and dynamics of the confined liquid different potentials are considered; a guest molecule with and without a dipole moment, and the host material with and without electrostatic charges. A layered structure of molecules inside the pores is observed. The monolayer is always well defined but when polar forces are included the mobility of the molecules is highly restricted and localized adsorption centers can be identified. The most probable orientation of molecules on the pore walls is discussed. Translational and rotational motions within the monolayer are highly hindered and they are slower for stronger attractive potentials. Diffusion of polar molecules in the pore center is faster than for nonpolar molecules. This effect is explained in terms of increased molecular packing near the pore walls caused by strong adsorbate–adsorbent interactions.