engleski

Supporting Anion and Heating Effect on Properties of Dry Layer-by-layer Assemblies Containing Poly(allylamine hydrochloride) and Poly(acrylic acid)

Polyelectrolytes are macromolecules (e.g. polymers) with dissociating functional groups which can carry positive or negative charge in solution. By alternating adsorption of positively and negatively charged polyelectrolytes on a charged surface, polyelectrolyte multilayers are formed. These nanocomposites have interesting properties and are applied in various scientific fields, mainly in biomedicine and pharmacology [1, 2]. In this study, ultrathin films have been fabricated on silicon wafers from layer-by-layer assembled poly(allylamine hydrochloride), PAH and poly(acrylic acid), PAA. Contact angle measurements, atomic force microscopy and ellipsometry were used to investigate the influence of the supporting sodium salt on the build-up and properties of PAH/PAA multilayer. It was found that the properties of prepared PAH/PAA multilayers follow the Hofmeister series. Thus, hydrophobicity, surface roughness, and film thickness increase in the order F− < Cl− < ClO4−. Interestingly, this ion-specific effect was suppressed when films were exposed to slight heating after each adsorption cycle. In this case, the choice of background salt didn’t affect wettability and surface roughness of PAH/PAA multilayer, but it affected the thickness of the film.

Polyelectrolyte multilayers ; Contact angle ; Atomic force microscopy ; Ellipsometry ; Ion-specific effect ; Heating

nije evidentirano