PHYSICOCHEMICAL ASPECTS OF POLYELECTROLYTE INTERACTIONS IN AQUEOUS FILM-FORMER DISPERSIONS

Abstract

Introduction. Waterborne coating materials offer environmental and technological advantages; however, the coatings they form may exhibit structural heterogeneity and increased porosity. One approach to controlling the properties of such systems is the introduction of functional modifiers. Objective. The aim of this study was to determine the effect of polyethylene polyamine on the surface and bulk properties of aqueous polyurethane and acrylic-polyurethane dispersions, as well as on the porosity of the coatings formed from them. Methodology. At 293 K, surface tension, specific and molar electrical conductivity, pH, and coating porosity were determined in systems containing 0-0.0024 mol/dm³ PEPA. Results and Discussion. In the binary «water-PEPA» system, changes in the character of the concentration dependences of surface tension, molar conductivity, and pH were observed in the region CPEPA = 0.0012 mol/dm³, corresponding to the critical association concentration. In ternary systems, the nature of changes in the investigated parameters depended on the film-former chemistry; the most pronounced decrease in surface tension was observed for the acrylic-polyurethane dispersion, from 39.60 to 35.15 mN/m. With increasing PEPA concentration, the porosity of the polyurethane coating decreased from 73.70 to 40.56%, while that of the acrylic-polyurethane coating decreased from 37.69 to 4.62%. Conclusion. The results demonstrate that PEPA affects the surface and bulk properties of the investigated aqueous dispersions and the structure of the coatings formed. The observed changes are consistent with the possibility of associative interactions between PEPA and the components of the studied systems, with the most pronounced modification effect established for the acrylic-polyurethane composition.