Hidrofobik yüzeylerin hazırlanması ve karakterizasyonu

Hydrophobic surfaces were prepared using two different methods. Emphasis hasbeen on controllability and better characterization of their wetting properties, which arecommonly classified under Wenzel and Cassie-Baxter regimes.With the intention to collect and interpret experimental data more efficiently, resultsof a pioneering numerical study (the model by Johnson and Dettre) were extended tosystems with controllable hydrophobicity. Analysis of the changes in contact angle andits hysteresis as a function of the same control parameter was shown to be an effectivemethod in the determination of the governing wetting regime.Polymer-nanoparticle composite films were studied as the first system. A slightlyhydrophobic amorphous polymer (polystyrene) was mixed with a fairly hydrophobicnanoparticle at varying mass percentages. This system allowed the control ofhydrophobicity by both chemical (composition) and physical (roughness) means.Collective analysis of contact angle and contact angle hysteresis data revealed thechemical effect to be more dominant for this system. In agreement with this conclusion,microscopy images and control experiments with a second type of nanoparticle showedthat dispersion of nanoparticles in the polymer matrix was strongly related to thehydrophobicity of the surfaces.The second method utilized self assembly property of a triblock copolymer (PCL-PDMS-PCL). Microphase separation in spin-coated films was tried to be used as atemplate for patterning the surface at different length scales. This patterning dependedsignificantly on the resulting morphology and the molecular orientation, and did notenhance hydrophobicity as expected. As an alternative way, solutions were prepared ina selective solvent and casted into films, which exhibited super-hydrophobic behavior.DLS and AFM analyses indicated formation of micellar structures at the micro- andnanometer level.iii