title: Molecular Mechanisms of ZnO Nanoparticle Dispersion in Solution: Modeling of Surfactant Association, Electrostatic Shielding and Counter Ion Dynamics.
abstract: Molecular models of 5 nm sized ZnO/Zn(OH)2 core-shell nanoparticles in ethanolic solution were derived as scale-up models (based on an earlier model created from ion-by-ion aggregation and self-organization) and subjected to mechanistic analyses of surface stabilization by block-copolymers. The latter comprise a poly-methacrylate chain accounting for strong surfactant association to the nanoparticle by hydrogen bonding and salt-bridges. While dangling poly-ethylene oxide chains provide only a limited degree of sterical hindering to nanoparticle agglomeration, the key mechanism of surface stabilization is electrostatic shielding arising from the acrylates and a halo of Na+ counter ions associated to the nanoparticle. Molecular dynamics simulations reveal different solvent shells and distance-dependent mobility of ions and solvent molecules. From this, we provide a molecular rationale of effective particle size, net charge and polarizability of the nanoparticles in solution.
authors.affiliation: Lehrstuhl für Theoretische Chemie/Computer-Chemie-Centrum Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbach Str. 25, Erlangen, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Duchstein
authors.affiliation: Lehrstuhl für Theoretische Chemie/Computer-Chemie-Centrum Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbach Str. 25, Erlangen, Germany.
authors.forename: Theodor
authors.initials: T
authors.lastname: Milek
authors.affiliation: Lehrstuhl für Theoretische Chemie/Computer-Chemie-Centrum Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbach Str. 25, Erlangen, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Zahn
mesh_terms: D007477:Ions / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D012996:Solutions; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D007477:Ions; D012996:Solutions; D013501:Surface-Active Agents; D015034:Zinc Oxide