The wetting phenomena related to superhydrophobic and superhydrophilic surfaces have been investigated over the past decade with attention on the micro and nano-scaled structures. Particularly, nanoparticles have been applied to create the structures and change surface wettability. In the present PhD work, it is aimed to produce extremely wettable and non- wettable surfaces out of Si02 nanoparticles and study the characteristics with respect to wetting and surface structures. The nanoparticles are presented and prepared in various solutions, which will be then deposited for the creation of micro and nano-scaled structures. Since the sizes of the individual nanoparticles are extremely small and different, the formed structures and therefore the wettability will be influenced accordingly. Various concentrations of nanoparticles in the solutions are set. The experiments are performed to characterise the wettability of the formed surfaces. The static contact angles are measured, while it is also needed to measure the advancing and receding contact angles for some cases, especially on the superhydrophobic surfaces. The structures of the surfaces are observed using Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM). It is noticed that the wettability of the formed surfaces is related to the concentration of nanoparticles, and the size can also make a difference in surface structures. The investigation further explores a variety of experimental conditions where the prepared solutions are promptly evaporated. This significantly changes the surface wettability and leads to very distinctive surface structures. The experimental work demonstrates that the surface structures and roughness play an important role in prompting the wettability of a solid surface. The distribution and assembling of Si02 nanoparticles on surfaces are connected to the processing conditions. Under these circumstances, the uniformity and consistency of the formed surface structures in micro and nano-scale are closely related to the size of nanoparticles. Thus, the use of Si02 nanoparticles for the creation of surface structures and the exhibited characteristics are reflected through the investigations and discussions in this PhD thesis. It sets up a platform to compare and examine the suitability of the theories for wetting phenomena on the formed surfaces, and provides good references for future work on the features of functional surfaces based on various nanoparticles.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:581967 |
| Date | January 2012 |
| Creators | Gao, Nan |
| Publisher | University of Nottingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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