title: Grand canonical Monte Carlo simulations of acetonitrile filling of silica pores of varying hydrophilicity/hydrophobicity.
abstract: Grand canonical Monte Carlo simulations have been used to determine the equilibrium density of acetonitrile in model amorphous silica pores with varying radius and surface chemistry. Pores of diameter approximately 2-4 nm were considered with different ratios of surface -OH moieties to -OC(CH(3))(3) groups. The calculations found that the acetonitrile density in the interior of all the pores is essentially identical with that of the bulk liquid. On the other hand, a slightly elevated liquid density is observed near the pore surface for pores with only -OH surface moieties. Replacement of surface -OH groups with -OC(CH(3))(3) units lengthens the liquid/pore interfacial region as acetonitrile molecules can insert themselves between the -OC(CH(3))(3) units. The results indicate that the major effect of changing the surface functionality comes from the differences in excluded volume rather than hydrogen-bonding effects. Finally, the choice of the acetonitrile potential can qualitatively change the results.
authors.affiliation: Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Tolga S
authors.initials: TS
authors.lastname: Gulmen
authors.forename: Ward H
authors.initials: WH
authors.lastname: Thompson
mesh_terms: D000097:Acetonitriles / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D009010:Monte Carlo Method; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry; D017155:Wettability
chemical_list: D000097:Acetonitriles; D014867:Water; D012822:Silicon Dioxide; C032159:acetonitrile