The layer-by-layer deposition method to prepare multilayers of polyelectrolytes of alternating charge has been followed in situ by means of optical reflectometry experiments. It turns out that in solutions containing both polyelectrolyte and appropriate salts up to a certain concentration, the regular build up of multilayers is modified and becomes an adsorption/redissolution process. We explain this by taking into account (i) that during the regular multilayer formation process the macromolecules cannot equilibrate, (ii) that the added salt plasticizes the multilayer to a state where the molecules are sufficiently mobile to enable them to equilibrate between the layer and the surrounding solution, and (iii) that the presence of excess polyelectrolyte brings the system to a one-phase region of the polyelectrolyte complex phase diagram, implying that polyelectrolyte complexes must dissolve under these conditions.

Complex coacervation core micelles were prepared with various polyelectrolytes and oppositely charged diblock copolymers. The diblock copolymers consist of a charged block and a water-soluble neutral block. Our experimental technique was dynamic light scattering in combination with titrations. At mixing ratios where the excess charge of the polyelectrolyte mixture is approximately zero, micelles may be formed. The colloidal stability of these micelles depends on the block lengths of the diblock copolymers and the molecular weight of the homopolymers. In addition, the chemical nature of the corona blocks and nature of the ionic groups of the polyelectrolytes also influence the stability and aggregation mechanism. A corona block that is three times longer than the core block is a prerequisite for stable micelles. If this ratio is further increased, the molecular weight of the homopolymers as well as the type of the ionic groups starts to play a major role. With very asymmetric block length ratios, no micelles are formed. In addition, if the neutral block is too short, the polymeric mixture forms a macroscopic precipitate. With a constant core block, the aggregation number decreases with increasing corona block length, as is predicted by scaling models for polymeric micelles with a neutral corona.

The layer-by-layer deposition method to prepare multilayers of polyelectrolytes of alternating charge has been followed in situ by means of optical reflectometry. It has been shown previously that in solutions containing both weak polyelectrolytes and appropriate salt the buildup of multilayers is modified and becomes an adsorption/dissolution process. The influence of different salts (phosphates, chlorides, and nitrates) and polyelectrolyte molecular weight on formation and erosion of multilayers on silica surfaces was investigated. In all experiments, the anionic polyelectrolyte was poly(acrylic acid). As the cationic polyelectrolyte, poly-(dimethylaminoethyl methacrylate), poly(allylamine hydrochloride), and poly(2-vinyl-N-methylpyridinium iodide) were used. It has been shown that at very low ionic strength (1 mM) regular buildup of multilayers is observed independent of the salt used. However, at higher ionic strength, dissolution also takes place, and the critical "glass-transition ionic strength" needed for the multilayer to be dissolved depends on the salt used, as well as on the polycation/polyanion pair studied.

Electrostatically driven coassembly of poly(acrylic acid)-block-poly(acrylamide), PAA-b-PAAm, and poly(2-methylvinylpyridinium iodide), P2MVP, leads to formation of micelles in aqueous solutions. Light scattering and small angle neutron scattering experiments have been performed to study the effect of concentration and length of the corona block (N PAAm ) 97, 208, and 417) on micellar characteristics. Small angle neutron scattering curves were analyzed by generalized indirect Fourier transformation and model fitting. All scattering curves could be well described with a combination of a form factor for polydisperse spheres in combination with a hard sphere structure factor for the highest concentrations. Micellar aggregation numbers, shape, and internal structure are relatively independent of concentration for C p < 23.12 g L -1 . The Guinier radius, average micellar radius, hydrodynamic radius, and polydispersity were found to increase with increasing N PAAm . Micellar mass and aggregation number were found to decrease with increasing N PAAm.

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