TiO2 films have attracted much attention because of their photoactivity and superhydrophilcity. For the superhydrophilicity studies, most research focused mainly on enhancing superhydrophilicity of Ti02 film under UV illumination. A hydrothermal-dip-coating superwetting TiO2 film was synthesised and found to preserve its superhydrophilicity up to 6 months. This non-UV superwetting TI02 film potentially opens an alternative application as bioactive layer for growing hydroxyapatite (HAP) coating, used extensively as prosthetic device medically. In this research, a systematic study was carried out, aiming to understand and optimise the hydrophilicity and superwetting properties of Ti O2 film without UV illumination. The effect of (i) PEG concentration, (ii) film thickness and (iii) agglomerate size of TiO2 on the wettability of TiO2 film was investigated. Although the presence of PEG does affect the porosity of the film, PEG concentration does not play significant role in retaining superhydrophilicity of the film. The evidence from AFM showed that surface roughness is the key parameter to control in order to retain the superhydrophilic wetting and antifogging behavior of the synthesised films, which can be tuned by simple manipulation of the multilayer assembled of TiO2 nanoparticles through varying the film thickness and agglomerate size. A film thickness of (????140nm) yielded the optimum roughness (rms =23nm) for the creation of the best superhydrophilic wetting behavior. Thicker films smoothened the film roughness, and therefore causing detrimental effects on their superhydrophilic wetting properties. Smaller agglomerate size was also found to be important in retaining the roughness film. The photoactivity of the "non UV illuminated"superhydrophilic film was found that be comparable with a Pilkington Activ??? in degrading methyl blue. The growth of Hydroxyapatite (HAP), synthesised via organic-inorganic hybrid method, and the mechanical stability of the HAP coating on the TiO2 films applied on titanium foil were studied. Homogenous HAP coating was found to grow only on the T O2 film with superhydrophilic properties. However the coating was of poor mechanical stability. Surface -OH was found to play an important role in aligning the phosphonate groups in HAP recursor during dip-coating.
| Identifer | oai:union.ndltd.org:ADTP/258613 |
| Date | January 2009 |
| Creators | Law, Woon Shin Clain, Chemical Sciences & Engineering, Faculty of Engineering, UNSW |
| Publisher | Awarded by:University of New South Wales. Chemical Sciences & Engineering |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Law Woon Shin Clain., http://unsworks.unsw.edu.au/copyright |
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