Ionic Inter-Particle Complexation Effect on the Performance of Waterborne Coatings

Maialen Argaiz; Fernando Ruipérez; Miren Aguirre; Radmila Tomovska

doi:10.3390/polym13183098

Ionic Inter-Particle Complexation Effect on the Performance of Waterborne Coatings

Polymers (Basel). 2021 Sep 14;13(18):3098. doi: 10.3390/polym13183098.

Authors

Maialen Argaiz¹, Fernando Ruipérez², Miren Aguirre¹, Radmila Tomovska^{1

3}

Affiliations

¹ POLYMAT and Departamento de Química Aplicada, Facultad de Ciencias Químicas, University of the Basque Country UPV/EHU, Joxe Mari Korta Zentroa, Tolosa Hiribidea, 72, 20018 Donostia-San Sebastián, Spain.
² POLYMAT and Physical Chemistry Department, Faculty of Pharmacy, University of the Basque Country UPV/EHU, 01006 Vitoria-Gasteiz, Spain.
³ Ikerbasque, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain.

Abstract

The performance of waterborne (meth)acrylic coatings is critically affected by the film formation process, in which the individual polymer particles must join to form a continuous film. Consequently, the waterborne polymers present lower performance than their solvent-borne counter-polymers. To decrease this effect, in this work, ionic complexation between oppositely charged polymer particles was introduced and its effect on the performance of waterborne polymer films was studied. The (meth)acrylic particles were charged by the addition of a small amount of ionic monomers, such as sodium styrene sulfonate and 2-(dimethylamino)ethyl methacrylate. Density functional theory calculations showed that the interaction between the selected main charges of the respective functional monomers (sulfonate-amine) is favored against the interactions with their counter ions (sulfonate-Na and amine-H). To induce ionic complexation, the oppositely charged latexes were blended, either based on the same number of charges or the same number of particles. The performance of the ionic complexed coatings was determined by means of tensile tests and water uptake measurements. The ionic complexed films were compared with reference films obtained at pH at which the cationic charges were in neutral form. The mechanical resistance was raised slightly by ionic bonding between particles, producing much more flexible films, whereas the water penetration within the polymeric films was considerably hindered. By exploring the process of polymer chains interdiffusion using Fluorescence Resonance Energy Transfer (FRET) analysis, it was found that the ionic complexation was established between the particles, which reduced significantly the interdiffusion process of polymer chains. The presented ionic complexes of sulfonate-amine functionalized particles open a promising approach for reinforcing waterborne coatings.

Keywords: 2-(dimethylamino)ethyl methacrylate; emulsion polymerization; inter-particle complexation; ionic complexation; meth(acrylic) latex; sodium styrene sulfonate; waterborne coating.