We have investigated the adsorption of strong polyelectrolytes mers on SiO 2 (6). As the adsorption proceeds, the surface (quaternized polyvinylpyridine (PVP / ) and quaternized dimethbecomes increasingly covered with polymer. At a certain ylaminoethyl methacrylate (AMA / )) and of a weak polyelectropoint the adsorption will be hindered. In this stage the rate lyte (AMA) onto TiO 2 and SiO 2 , using reflectometry. Two characof adsorption depends also on the attachment process. At an teristic properties, i.e., the initial adsorption rate and the amount even higher coverage, the rate becomes independent of the adsorbed, were studied as functions of ionic strength and pH. Also, transport process and the attachment is completely rate-limthe effects of the molar mass of the polymers, of the type and iting until the plateau value is reached.
valence of the ions, and of the surface charge and the segment charge were investigated. We find that the initial adsorption rate Usually, only the plateau value of the adsorbed amount is usually determined by the rate of transport to the surface, and is studied. The adsorbed amount is determined by the balance therefore by the diffusion coefficient, which depends on the size between all interactions in the system. The electrostatic interof the molecule. The amount adsorbed is determined by a balance actions, which play a key role in polyelectrolyte adsorption, between the interactions in the system. For PVP / adsorbing on are (i) the interaction between the substrate and the polymer TiO 2 , these interactions are mainly electrostatic, but on SiO 2 a segments and (ii) the mutual interaction between the charged nonelectrostatic affinity of PVP / for the surface also plays a role.
segments, which always opposes adsorption. On an oppo-
The adsorption of AMA / and AMA on TiO 2 is purely electrostatic.
sitely charged surface, these interactions favor a flat confor-Upon adsorption of AMA / the surface adjusts its charge. In the mation, in which the segments are mainly situated in trains.
case of adsorption of AMA both the surface and the segment
In such a conformation the interaction between the segments charge are regulated. This regulation process reduces the buildup of the electrostatic potential on the surface and enables more poly-and the surface is maximized. When the surface charge is mer molecules to adsorb.