• Jeanette Rosa Pedersen
4. semester, Kemi, Kandidat (Scient) (Kandidatuddannelse)
It was attempted to modify Cu, Al, and Cr surfaces by the use of a polystyrene template. The aim of the modification was a rough surface with a high water contact angle (CA). It was attempted to create the polystyrene (PS) template by a combination of a thin liquid film deposition (TLFD) technique and an electric potential. The TLFD technique was applied to utilize lateral capillary forces. The electric potential was applied because it, in literature, had been observed to enhance the lateral capillary forces. It was desired to achieve a template of closed-packed (CP) particles in mono-layer with a hexagonal lattice on the metal surfaces, to obtain the smallest solid fraction possible. Scanning electron microscopy and contact angle measurements were used to analyse the samples. Furthermore, dynamic light scattering was used to analyse the particles. The characterization of the metal surfaces showed large crystals on the Al surface. Therefore, Al was not used for further experiments. Cr had a porous surface and a CA of 95 +/- 12 degrees. Cu had a planar surface and a CA of 84 +/- 7 degrees. From experiments using the TLFD technique and glass slides, a PS concentration of 24 g/L and the withdrawal rates of 3 x 10^(-2) and 1 x 10^(-1) mm/s were found to be optimal for further investigations. The metal surfaces responded differently to the TLFD technique than the glass slides. This seemed to be caused by different surface structures and wettabilities of the surfaces. With the TLFD technique multi-layers were formed on the metal surfaces. Therefore, a positively charged potential was applied on the surface. Cr was not conductive, thus, the effect of the potential could only be considered from the Cu samples. The potential resulted in particles being repelled from the surface, and a thinner film was achieved. The effect was distinct when applying a potential of 300 mV. CP particle mono-layer with a hexagonal lattice were observed in some areas of the surfaces. It was attempted to remove the particles from gold coated samples. Heating of the sample for 2 hours at 550 degrees celcius resulted in crystals of several micrometers on the surface. Furthermore, the particles seemed to have shrunk, but had not been removed. The particles had also not been removed by the wash with toluene for 43 hours, but the sonication of samples in toluene for 5 minutes seemed to be the most effective method.
Udgivende institutionAAU
ID: 14419749