Stable TiO 2 dispersions for nanocoating preparation

• Published in: Surface & coatings technology Vol. 204; no. 9; pp. 1445 - 1451
• Main Authors: Veronovski, N., Andreozzi, P., La Mesa, C., Sfiligoj-Smole, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2010
• Subjects: Cationic and anionic surfactants; Coatings; Self-cleaning; SEM analysis; Size and ζ-potential characterization; TiO 2 P25; SEM analysis; Cationic and anionic surfactants; TiO 2 P25; Self-cleaning; Coatings; Size and ζ-potential characterization
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2009.09.041

In this research the preparation and characterization of titanium (TiO 2) coated self-cleaning cellulose materials starting from TiO 2 P25 powder (Degussa, Germany) was studied. The aim of the research was to decrease high aggregation of TiO 2 P25 nanoparticles, using surfactant species as dispersant and/or stabilisers (considering the balance between repulsive and attractive forces), in view of the fact that TiO 2 nanoparticles, when optimally separated into smaller particle populations, present the best properties in the system they are used in (coatings). For this purpose cationic alkanediyl- α, ω-bis-N-dodecyl-N, N′-dimethyl-ammonium bromide (Gemini) and anionic sodium dodecyl sulphate (SDS) surfactants were applied, with concentrations under their CMSs. Size and zeta-potential ( ζ-potential) characterization of stable colloidal dispersions were performed. For stable 0.5, 2.5 and 5.0 mg/mL TiO 2 dispersions in the presence of 250 × 10 − 6 mol/L Gemini surfactant ( ζ-potential ~ 40 mV) only two scattering populations were determined, at 78–95 nm and at ~ 280 nm. As a proof of stabilized TiO 2 P25-surfactant colloidal dispersions uniform coatings were obtained, generated at the fibre surfaces, which were analyzed by scanning electron microscopy (SEM). With the usage of proper amounts of surfactants, homogeneous thin TiO 2 coatings were formed. Superior dense coatings on the fibre surfaces were formed after treatment in 5.0 mg/mL aqueous TiO 2 P25 dispersions, in the presence of 250 × 10 − 6 mol/L Gemini surfactant in 5.0 × 10 − 3 mol/L KBr at 25 °C. In addition to that, self-cleaning test was performed. Higher photocatalytic activity was determined for samples with denser coatings. Fibres with thin coatings had a lack of photocatalytic activity.