Influence of topography and surface chemistry on the wetting properties ofTiO2-based ceramic coatings

Mikael Järn

Influence of topography and surface chemistry on the wetting properties ofTiO2-based ceramic coatings

Mikael Järn
Pehmeäkantinen
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Myymäläsaatavuus

Tuotetiedot

  • Näytä kaikki
    • Kustantaja Åbo Akademis bibliotek
    • ISBN 9789521224706
    • Kirjoittajat Mikael Järn
    • Kieli englanti
    • Tuotepääryhmä 02
    • Tuotelinja 1
    • Sivumäärä 76
    • Kirjastoluokka 54
    • Uusintapainoksen pvm 01.01.2010
    • Tuotemuoto Pehmeäkantinen kirja

Myymäläsaatavuus

Tuotetiedot

  • Näytä kaikki
    • Kustantaja Åbo Akademis bibliotek
    • ISBN 9789521224706
    • Kirjoittajat Mikael Järn
    • Kieli englanti
    • Tuotepääryhmä 02
    • Tuotelinja 1
    • Sivumäärä 76
    • Kirjastoluokka 54
    • Uusintapainoksen pvm 01.01.2010
    • Tuotemuoto Pehmeäkantinen kirja

Tuoteryhmät

Tuotekuvaus

The wetting properties of solids are important in many natural systems as well as in a wide range of technical applications. It is well-know that the wettability of a solid surface is governed by both the surface chemistry and the surface structure. In this thesis, the wettability of TiO2-based ceramic coatings was studied. The coatings were prepared by utilizing sol-gel dip-coating technology.

In the first part of the thesis, one component TiO2 coatings with random heterogeneities were studied. The topography of the coatings was varied by changing the synthesis conditions, e.g. calcination temperature and with the addition of additives. The topography of the coatings was described with a series of roughness parameters. It was shown that the often used root mean square roughness (RMS) is not sufficient enough to describe the topography of a surface. The influence of surface topography on the wetting properties was also studied. Furthermore, the combined effect of topography and surface wettability on the precipitation kinetics of calcium phosphate (CaP) on the coatings was investigated. It was found that a hydrophilic coating together with a specific surface structure is more favorable to initiate the formation of CaP.

In the next step, strongly water-repellant coatings were prepared by the spontaneous formation of CaP followed by hydrophobization with a perfluorophosphate surfactant. The superhydro hobicity could be explained by the morphology of the coating, where the solid-liquid contact was minimized.

In the second part of the thesis, well-ordered nanopatterns of TiO2 on silica or gold substrates were prepared with the evaporation induced self-assembly (EISA) technique. The material consists of a very thin layer of titania, where the substrate is accessible through hexagonally ordered nanocraters aligned perpendicularly to the surface. Such nanopatterned surfaces are ideal model systems for detailed wettability studies, since the titania network and the substrate (SiO2 or Au) can be selectively functionalized with various organic molecules. The influence of the geometry (pore diameter, wall thickness, layer thickness) and hydrophilic-hydrophobic contrast on the wetting properties were studied. The experimental results could successfully be modeled with existing theories for the wetting of rough and heterogeneous surfaces.