Cambridge 7th to 9th September
article posted 27 Apr 2015
Barbora Holubová graduated in Chemistry of Materials and Materials Engineering with specialization to Technology of Conservation and Restoration from the University of Chemistry and Technology Prague in 2014 for pursuing directly her PhD at the same place at the Department of Glass and Ceramics.
Her main field of study is the problematic of glass corrosion with a special focus on means of glass protection. Her work focuses now on the potential use of hybrid inorganic-organic silica based coatings in the field of conservation-restoration practice and building maintenance; together with evaluation of the interaction processes of thin films on glass substrates.
Investigation on protective hybrid silica coatings on historical glass: Comparative study and new approaches
Barbora Holubová1,*, Zuzana Zlámalová Cílová1,
Irena Kucerová2, Ales Helebrant1
Historical stained glass or glass mosaics are an integral part of a very fragile and valuable heritage placed on many civil and religious buildings. As such an exterior architectural glass preferably remains in its original surrounding, it is heavily endangered by weathering phenomena. Since the protective glazing does not eliminate completely weathering issues, there is a strong interest in the application of protective coatings which have been used with mixed success since the beginning of the last century. More recently, the attention has been focused particularly on development of advanced hybrid organic-inorganic silicon-based coatings. Their main asset consists in the dual structure characteristic: an inorganic part (heteropolysiloxane backbone) is capable of strong, covalent siloxane bond to glass surfaces, and an organic part (containing different organic functionalities) can provide progress in overall performance of a final coating.
In this study, we investigated newly designed hybrid silica coatings prepared via the sol-gel process consisting in mixing a silica-based inorganic matrix (tetraethyl orthosilicate) with different quantities of Si-alkoxides functionalized with various organic groups. In addition, we analysed also the influence of possible multi-layering and addition of different substances modifying final flow properties. All the tested coatings were dip-coated onto the glass samples at low temperatures without any heat treatment. Besides that, also some of already existing commercial hybrid silica products were tested. The samples were analysed before and after different model aging tests simulating various weathering parameters. After aging, the best performing coatings showed good overall homogeneity and transparency (optical and scanning electron microscopy), improved water repellency and adhesion to the glass substrate (static contact angle measurements, cross-cut tape tests) and no colour or chemical composition shifts (UV-VIS, FTIR). In general, we approved that these transparent low temperature coatings, easily applicable to thin films, appear to satisfy the main requirements for the protection of glass exposed to weathering phenomena.
The authors would like to thank the Ministry of Culture, Czech Republic, for financially supporting this research under the project DF12P01OVV017.
1)Department of Glass and Ceramics, University of Chemistry and Technology, Technická 5, Prague, Czech Republic
2)Department of Chemical Technology of Monument Conservation, University of Chemistry and Technology, Technická 5, Prague, Czech Republic