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173(1-3) (2000), 39-49
The alternate adsorption processes of polyelectrolytes from solution have been investigated in situ using a functionalized (gold electrode) quartz substrate via the quartz crystal microbalance (QCM) technique. The deposition process involved the alternate layer by layer electrostatic (Coulombic) interaction between oppositely charged adsorbing polyelectrolytes resulting in ultrathin multilayer films. Three kinds of polyelectrolyte combinations were used: poly(diallyldimethylammonium chloride) (PDADMAC), poly(ethylenimine) (PEI) and poly(allylamine hydrochloride) (PAH) as the cationic polymers and poly(sodium-4- styrensulfonate) (PSS) as the anionic polymer for polycation/ polyanion combinations. The electrical behavior of the piezoelectric 'quartz crystal' was sensitive to the adsorption properties of the polyelectrolytes, thus allowing dose observation of the time-dependent adsorption processes. The adsorption relationship was explored for different polyelectrolyte pair-combinations, alternate solution concentration and the presence of rinsing and drying steps. The results showed that the amount of frequency change is mostly dependent on the immediate subphase environment of the crystal surface, i.e. aqueous environment versus air in relation to the classic Sauerbrey equation. (C) 2000 Elsevier Science B.V. All rights reserved.

[56] Influence of the Ionic-Strength on the Structure of Polyelectrolyte Films at the Solid/Liquid Interface

R. Steitz, V. Leiner, R. Siebrecht and R. Vonklitzing

Colloid Surf. A 163(1) (2000), 63-70

The structure of polyelectrolyte multilayers built up by alternate adsorption of polyanions and polycations is investigated by X-ray reflectivity at the solid/air and neutron reflectivity at the solid/liquid interface. The experiments provide detailed information about the density gradient of polyelectrolyte chains across the film and show the influence of the water content of the film on the internal structure. The polyelectrolyte density is determined by the adsorption conditions (e.g. amount of NaCl) and cannot be changed by addition of salt after adsorption. After drying the film thickness is reduced by 30%. (C) 2000 Elsevier Science B.V. All rights reserved.

[57] Electrostatic Adsorption of Polystyrene Particles with Different Surface-Charges Onto the Surface of an Ultrathin Polymer Film

T. Serizawa, S. Kamimura and M. Akashi

Colloid Surf. A