Stabilization of nano-TiO2 aqueous dispersions with poly(ethylene glycol)-b-poly(4-vinyl pyridine) block copolymer and their incorporation in photocatalytic acrylic varnishes

• Published in: Progress in organic coatings Vol. 77; no. 11; pp. 1741 - 1749
• Main Authors: Monteiro, S., Dias, A., Mendes, A.M., Mendes, J.P., Serra, A.C., Rocha, N., Coelho, J.F.J., Magalhães, F.D.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2014
• Subjects: Amphiphilic copolymers; Aqueous dispersion; Block copolymers; Clusters; Dispersants; Dispersions; Nanoparticles; Photocatalysis; Photocatalytic titanium dioxide; Pyridines; Stability; Stabilization; Titanium dioxide; Waterborne acrylic varnish; Nanoparticles; Waterborne acrylic varnish; Stability; Amphiphilic copolymers; Aqueous dispersion; Photocatalytic titanium dioxide
• ISSN: 0300-9440; 1873-331X
• DOI: 10.1016/j.porgcoat.2014.05.030

•Nano-TiO2 aqueous dispersions stabilized using novel mPEG-b-P4VP block copolymers.•For nanoparticles deagglomeration, ultrasonication proved to be the best technique.•Block copolymers had better stability than conventional polyelectrolyte dispersant.•Varnishes with TiO2/copolymers had better transparency and photocatalytic activity. In this work, TiO2 nanoparticles were dispersed and stabilized in water using a novel type of dispersant based on tailor-made amphiphilic block copolymers of poly(ethylene glycol)-block-poly(4-vinyl pyridine) (mPEG-b-P4VP) prepared by atom transfer radical polymerization (ATRP). The performance of this new block copolymer as dispersant was compared to a polyelectrolyte dispersant commonly used for TiO2, sodium salt of polyacrylic acid (Na-PAA). The effect of dispersion technique and type and amount of dispersant on deagglomeration and stability of the TiO2 aqueous suspensions were studied. After incorporation in a standard waterborne acrylic varnish formulation, dry film transparency, photocatalytic activity, and nanoparticle cluster size were also evaluated. The results show that mPEG-b-P4VP copolymer with appropriate block lengths can have a better performance than Na-PAA in terms of aqueous dispersion stabilization and cluster size reduction in the acrylic matrix. This translates into higher film transparency and photocatalytic performance.