|Tipo di tesi||Tesi di dottorato di ricerca|
|Autore||CEDILLO GONZALEZ, ERIKA IVETH|
|Titolo||Studio e sviluppo di materiali avanzati per l’architettura e l’edilizia: preparazione e caratterizzazione di rivestimenti di TiO2 per materiali da costruzione.|
|Titolo in inglese||Study and development of advanced materials for architecture and construction: preparation and characterization of TiO2 coatings for building materials.|
|Settore scientifico disciplinare||ING-IND/22 - SCIENZA E TECNOLOGIA DEI MATERIALI|
|Corso di studi||Scuola di D.R. in MODELLISTICA, SIMULAZIONE COMPUTAZIONALE E CARATTERIZZAZIONE MULTISCALA PER LE SCIENZE DEI MATERIALI E DELLA VITA|
|Data inizio appello||2014-02-27|
|Disponibilità||Accessibile via web (tutti i file della tesi sono accessibili)|
Oggigiorno, l'uso di rivestimenti di TiO2 fotocatalitico depositati su componenti edilizi sta diventando molto interessante per lo sviluppo di materiali autopulenti. La proprietà autopulente della TiO2 è esprimibile in termini di reazione redox fotoindotta di inquinanti adsorbiti e super- idrofilia fotoindotta della superficie quando è irradiata con energia ultravioletta. Entrambi i fenomeni sono stati ampiamente utilizzati nella progettazione di diversi tipi di materiali da costruzione con caratteristiche autopulenti. Infatti, alcuni di essi sono ad oggi disponibili in commercio. Tuttavia, le limitazioni correlate con l'ottenimento di prodotti efficaci e la loro applicazione in condizioni d’uso (atmosferiche, per l’ordinaria manutenzione e pulizia) impediscono ancora un loro diffuso uso nel settore dell'edilizia. Pertanto, in questo lavoro, diversi studi sono stati condotti su queste principali limitazioni allo scopo di promuovere un più vasto utilizzo dei materiali autopulenti contenenti TiO2 nell’edilizia.
Nowadays, the use of photocatalytic TiO2 coatings deposited over building components becomes more attractive for the development of self-cleaning materials. The self-cleaning property of TiO2 is explained in terms of both photoinduced redox reaction of adsorbed pollutants and photoinduced super-hydrophilicity of its surface when irradiated with ultra band gap energy. These phenomena have been widely exploited to design different kinds of self-cleaning building materials. Indeed, some of them are commercially available. However, limitations correlated with the obtaining of efficient products and their application at real conditions still prevent their employment in the building sector. Therefore, in this work, investigations regards these limitations were carried out with the aim of promoting a widespread use of TiO2-based self-cleaning materials in the building industry. The research was divided in two principal aspects: (i) issues associated with the production of TiO2 self-cleaning materials and (ii) limitations associated with the utilization of self-cleaning coatings at real conditions. Between the limitations associated with the production of self-cleaning materials there are the low adhesion of the coatings to their substrate, the use of substrates that affect the photocatalytic activity (or PCA) and the presence of residues from the catalyst synthesis that could compromise the PCA of the final products. In this research, improvements of the adhesion between TiO2 coatings and soda-lime glasses were reached throughout roughness modifications of the glasses using chemical treatments. Furthermore, this procedure also decreased the surface Na+ from the glass surface, avoiding reductions on the PCA of the final products due to sodium contamination. The problems associated to the presence of residues from synthesis were overcome by chemical treatments of the as-prepared products. Regards the limitations associated with the application of self-cleaning coatings at real conditions, the most common include weathering and the changes in PCA associated to atmospheric variables such as temperature and humidity. Weathering not only affects the PCA but also promotes the release of nanoparticles, being dangerous for the environment or the human health. On the other hand, temperature and humidity are known to influence the reaction pathways and the kinetics of the organic degradation process. Here, TiO2 coatings were exposed to weathering and different values of temperature and humidity in order to evaluate the effects of these phenomena on the self-cleaning property of the coatings. In addition, to determine how the surface characteristics of the coating influence the self-cleaning property at real conditions, three different types of morphologies (nanoparticled, mesoporous and non-porous TiO2) were tested. The information obtained in this work permitted not only to overcome some typical limitations associated with the production of self-cleaning glasses, but also to establish the real conditions at which each one of these materials should present better performances. In addition, guidelines for an adequate choosing of the kind of TiO2 coating depending on their performance at determinate conditions and the target application have been proposed, making these materials even more interesting for the building sector from both commercial and practical points of view.