title: Structure of adsorbed polyelectrolyte monolayers investigated by combining optical reflectometry and piezoelectric techniques.
abstract: Polyelectrolyte monolayers on solid substrates are studied with optical reflectivity and the quartz crystal microbalance (QCM). In particular, we investigate the adsorption of anionic poly(styrene sulfonate) (PSS) on amino-functionalized silica as well as cationic poly(allylamine hydrochloride) (PAH) and poly-L-lysine (PLL) on bare silica. By comparing the dry and wet masses measured on identical substrates with these two techniques, we obtain information on the layer thickness and water content of these layers. Monolayers typically feature an adsorbed dry mass of about 0.1-2 mg/m(2), a layer thickness of 0.5-2 nm, and a water content of 20-50%. One finds that the layer thickness increases with increasing concentrations of monovalent salts and polyelectrolytes.
authors.affiliation: Departement of Inorganic, Analytical and Applied Chemistry, University of Geneva, Geneva, Switzerland.
authors.forename: Maria
authors.initials: M
authors.lastname: Porus
authors.forename: Plinio
authors.initials: P
authors.lastname: Maroni
authors.forename: Michal
authors.initials: M
authors.lastname: Borkovec
mesh_terms: D000327:Adsorption; D004560:Electricity; D004573:Electrolytes / Q000737:chemistry; D055620:Optical Phenomena; D011137:Polystyrenes / Q000737:chemistry*; D058525:Quartz Crystal Microbalance Techniques; D014867:Water / Q000737:chemistry
chemical_list: D004573:Electrolytes; D011137:Polystyrenes; D014867:Water; C003321:polystyrene sulfonic acid