Abstract
Positively charged water-solid interfaces are prepared by adsorption of a cationic polyelectrolyte poly(diallyldimethylammonium chloride) (PDADMAC) from aqueous solutions to planar silica substrates. These substrates are characterized by atomic force microscopy (AFM), optical reflectivity, and streaming current measurements. By tuning the amount of adsorbed polyelectrolyte, the surface charge of the substrate can be systematically varied. These substrates are further used to study deposition of sulfate latex nanoparticles, which is also accomplished by optical reflectivity. This deposition process is found to be consistent with an extension of the random sequential adsorption (RSA) model in a semi-quantitative fashion. Such deposition studies were further used to ascertain that the substrates obtained by in situ and ex situ functionalization behave in an identical fashion.
Highlights
Polyelectrolytes are known to adsorb strongly and irreversibly from aqueous solutions to oppositely charged substrates [1,2,3,4]
We further studied studied depositionare of obtained polystyrene latex nanoparticles to these substrates with deposition reflectomof polystyrene latex nanoparticles to these substrates with reflectometry and atomic force microscopy (AFM) strongly imaging
We found that the deposited mass of the nanoparticles strongly depends on the ionic depends on the ionic strength and the charge density of the substrate
Summary
Polyelectrolytes are known to adsorb strongly and irreversibly from aqueous solutions to oppositely charged substrates [1,2,3,4]. Several systems of this kind are known, those involving cationic polyelectrolytes and negatively charged substrates. The adsorption process is basically irreversible, meaning that once these films have formed, they remain very stable in polyelectrolyte-free electrolyte solutions. Another important feature of these films is that they induce a charge reversal (or overcharging) of the substrate, leading to positively charged surfaces in the case of cationic polyelectrolytes
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