title: Polymer multilayer film formation studied by in situ ellipsometry and electrochemistry.
abstract: Polyelectrolyte multilayer films adsorbed on gold surfaces were studied by combined ellipsometric and electrochemical methods. Multilayers were composed of "synthetic" (poly(4-styrenesulfonic acid) ammonium salt (PSS) and poly(allylamine hydrochloride) (PAH) (PSS/PAH)) and "semi-natural" (carboxymethyl cellulose (CMC) and chitosan (CHI) (CMC/CHI)) polyelectrolytes. It was found that only PSS/PAH Layer-by-Layer (LbL) assembled structures result in dense surface confined films that limit permeability of small molecules, such as ferri-/ferrocyanide. The PSS/PAH assemblies can be envisaged as films with pinholes, through which small molecules diffuse. During the LbL deposition process of these films a number of pinholes quickly decay. A representative pinhole diameter was found to be approximately 20 microm, which determines the diffusion of small molecules through LbL films, and yet remains constant when the film consists of a few LbL assembled polyelectrolyte bilayers. CMC/CHI LbL assemblies at gold electrode surfaces give very low density films, which do not limit the diffusion of ferri-/ferrocyanide between the surface of the electrode and the solution.
authors.affiliation: Biomedical Laboratory Science and Technology, Faculty of Health and Society, Malmö University, SE-205 06 Malmö, Sweden. karolina.haberska@mah.se
authors.forename: Karolina
authors.initials: K
authors.lastname: Haberska
authors.forename: Tautgirdas
authors.initials: T
authors.lastname: Ruzgas
mesh_terms: D000327:Adsorption; D002266:Carboxymethylcellulose Sodium / Q000737:chemistry; D048271:Chitosan / Q000737:chemistry; D004058:Diffusion; D017097:Electric Impedance; D004563:Electrochemistry; D004573:Electrolytes / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D010084:Oxidation-Reduction; D011108:Polymers / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D004573:Electrolytes; D011108:Polymers; D006046:Gold; D048271:Chitosan; D002266:Carboxymethylcellulose Sodium