Durable self-cleaning coatings for architectural surfaces by incorporation of TiO2 nano-particles into hydroxyapatite films

Enrico Sassoni, Eros D'Amen, Norberto Roveri, George W. Scherer, Elisa Franzoni

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

To prevent soiling of marble exposed outdoors, the use of TiO2 nano-particles has been proposed in the literature by two main routes, both raising durability issues: (i) direct application to marble surface, with the risk of particle leaching by rainfall; (ii) particle incorporation into inorganic or organic coatings, with the risk of organic coating degradation catalyzed by TiO2 photoactivity. Here, we investigated the combination of nano-TiO2 and hydroxyapatite (HAP), previously developed for marble protection against dissolution in rain and mechanical consolidation. HAP-TiO2 combination was investigated by two routes: (i) sequential application of HAP followed by nano-TiO2 ("H+T"); (ii) simultaneous application by introducing nano-TiO2 into the phosphate solution used to form HAP ("HT"). The self-cleaning ability was evaluated before and after prolonged exposure to simulated rain. "H+T" and "HT" coatings exhibited much better resistance to nano-TiO2 leaching by rain, compared to TiO2 alone. In "H+T" samples, TiO2 nano-particles adhere better to HAP (having flower-like morphology and high specific surface area) than to marble. In "HT" samples, thanks to chemical bonds between nano-TiO2 and HAP, the particles are firmly incorporated in the HAP coating, which protects them from leaching by rain, without diminishing their photoactivity and without being degraded by them.

Original languageEnglish (US)
Article number177
JournalMaterials
Volume11
Issue number2
DOIs
StatePublished - Jan 23 2018

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

Keywords

  • Anatase
  • Calcium phosphates
  • Consolidation
  • Cultural heritage
  • Leaching
  • Marble
  • Photocatalytic activity
  • Protection
  • Rain
  • Soiling

Fingerprint Dive into the research topics of 'Durable self-cleaning coatings for architectural surfaces by incorporation of TiO<sub>2</sub> nano-particles into hydroxyapatite films'. Together they form a unique fingerprint.

Cite this