title: Single molecule experiments visualizing adsorbed polyelectrolyte molecules in the full range of mono- and divalent counterion concentrations.
abstract: This work provides direct experimental verification (on the level of single molecules) for the behavior of hydrophobic polyelectrolyte chains adsorbed at a solid-liquid interface in the full range of possible salt concentrations: (a) in a dilute salt solution, PE chains possess an extended coil conformation visualized as adsorbed 2D-equilibrated coils; (b) in a moderate salt concentration range, the polymer coil shrinks and approaches the dimensions of a polymer coil under θ-conditions and the chains are visualized as adsorbed 3D-projected coils; (c) at high salt concentrations, the polymer coils reexpand and the molecules are visualized as 2D-equilibrated extended coils; however, (d) reexpansion is limited in the presence of multivalent counterions, presumably due to the bridging of the polymer coils by the counterions.
authors.affiliation: Department of Chemistry and Biomolecular Science, Clarkson University, 8 Clarkson Avenue, Potsdam, New York 13699, USA.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Roiter
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Trotsenko
authors.forename: Viktor
authors.initials: V
authors.lastname: Tokarev
authors.forename: Sergiy
authors.initials: S
authors.lastname: Minko
mesh_terms: D000327:Adsorption; D004573:Electrolytes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D011108:Polymers / Q000737:chemistry*; D012492:Salts / Q000737:chemistry; D013499:Surface Properties
chemical_list: D004573:Electrolytes; D011108:Polymers; D012492:Salts