Creating hydrophobic and hydrophilic surfaces with PECVD method for continuous and efficient fog collection

Fog harvesting from the air is one of the sustainable and effective methods to obtain fresh water. Energy-free fog collector systems are widely used for this purpose, but the efficiency of traditional meshes used in these systems is not sufficient. The main objective of this thesis is to transform ordinary polypropylene fabrics into effective fog harvesting materials by coating them with polymeric thin films using plasma enhanced chemical vapor deposition (PECVD) method, which is a one-step and environmentally friendly method. Poly(acrylic acid) (PAA) and poly(2,3,4,4,4-hexafluorobutyl acrylate) (PHFBA) thin films were synthesized using PECVD method as hydrophilic and hydrophobic polymers, respectively. The effects of surface wettability and fabric weight on fog harvesting efficiency were investigated. Moreover, the effect of surface roughness on fog harvesting efficiency was studied. For this purpose, modified silica particles were synthesized and used to increase the roughness of the fabrics. Based on the results of this thesis, the synergistic effect of the hydrophobic film coating by PECVD and the porosity created by the modified silica particles increased the fog harvesting efficiency of the fabrics. The fabrics produced with hydrophobic thin film coatings on the roughened surface showed the highest fog harvesting efficiency (1,14 L m-2 h). The results of this thesis show that the fabrics modified by the method developed here can be a promising alternative to the meshes currently used in fog collectors. Considering the scale up potential of PECVD system, it is possible to modify much larger surface areas for fog harvesting. Furthermore, the surface modification techniques developed here can be applied to develop materials for applications where wettability is important, such as microfluidics, lab-on-a-chip, sensors and agriculture.