Colloidal Stability of Positively Charged Dispersions of Styrene and Acrylic Copolymers in the Presence of TiO₂ and CaCO₃

• Main Authors: Kamil Wojciechowski, Małgorzata Gutarowicz, Kamil Janke, Ilona Jurek, Marcin Kaczorowski, Jolanta Mierzejewska, Paweł Parzuchowski
• Format: Article
• Language: English
• Published: MDPI AG 2019-01-01
• Series: Colloids and Interfaces
• Subjects: latex; antimicrobial coatings; titania; paints; CTAB
• Online Access: https://www.mdpi.com/2504-5377/3/1/20

Increasing antibiotic resistance of several pathogenic microorganisms calls for alternative approaches to prevent spreading of bacterial diseases. We propose to employ for this purpose coatings obtained from positively charged latex dispersions. In this contribution we characterize aqueous mixed dispersions containing TiO₂ or CaCO₃ and methyl methacrylate-ethyl acrylate or styrene-ethyl acrylate copolymers synthesized using a cationic surfactant, cetyltrimethylammonium bromide as an emulsifier. Particle size, electrokinetic (ζ) potential of the mixed dispersions and the resulting thin films, as well as antimicrobial properties of the latter are described. The TiO₂ and CaCO₃ dispersions were stabilised with polyethyleneimine (PEI) and optimum pH for the mixed dispersions were chosen on the basis of ζ-potential measurements. For TiO₂, the maximum ζ = +35 mV was found at pH 7.5, and for CaCO₃, pH was set at 8.2 (ζ = +38 mV), to prevent its dissolution. In most 1:1 mixtures of TiO₂ or CaCO₃ with the cetyltrimethylammonium bromide (CTAB)-stabilised latex dispersions, two distinct particles populations were observed, corresponding to the bare latex and bare TiO₂ or CaCO₃ fractions. Films made of the mixed dispersions remained positively charged and showed antimicrobial activity similar or reduced with respect to the bare polymer films.