소수성 개질된 흄드 실리카를 첨가한 PVDF 도료의 특성 분석

Abstract

In recent years, superhydrophobic surfaces have attracted much attention because they have properties like anti-sticking, anti-icing, anti-contamination, anti-corrosion, and self-cleaning etc. Utilizing these properties, it is used in many areas such as exterior wall of building, radome, blade of wind turbine, gas pipelines, etc An example of the superhydrophobic surface from nature is the lotus leaf, if a water droplet on this surface, a water droplet forms a sphere and easily rolls off. This is called “lotus effect” or “self-cleaning effect” which is obtained by combining a surface topography with micro and nano structure and low surface energy. By mimicking these conditions, artificial superhydrophobic surfaces can be fabricated. Several studies using PVDF(polyvinylidene fluoride) and hydrophobically modified fumed silica have been published. However, in most of studies, commercialized hydrohphobic fumed silica was used and the changes of hydrophobicity and properties of PVDF coatings depending on the variation of the content of hydrophobic fumed silica added to the PVDF coatings are mainly studied. In this paper, two types of silane modifiers, trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDZ), were used to hydrophobically modify the fumed silica, and the hydrophobic property and property changes of PVDF coating were studied according to the amount of modifier used in modification process of fumed silica. Changes in the composition of the fumed silica after the surface modification were analyzed by Fourier transform infrared, x-ray photoelectron spectroscopy, elemental analysis. The dispersibility of fumed silica after surface modification was analyzed by transmission electron microscopy, particle size analyze. The change of hydrophocity of PVDF coating were analyzed by water contact angle. Surface properties were analyzed by field emission scanning electron microscopy and scanning probe microscopy. The stain resistance test of PVDF coatings was carried out by immersing the solution consisting of 0.5 wt% carbon black and 99.5 wt% distilled water for 2 hours and measuring the color difference before and after immersion. potentiodynamic polarization was measured using a 0.35 wt% NaCl solution in order to confirm that the anti-corrosion property improved as the hydrophobicity of the PVDF coating increased, and compared with PVDF coating containing AEROSIL® R816 and R976 as commercialized hydrophobic fumed silica. As a result of the surface properties analysis, it was confirmed that the average surface roughness was increased and the water contact angle of coating was improved as the content of the modifier used in the surface hydrophobic modification process of the fumed silica added to coating was increased. The results of potentiodynamic polarization measurement showed that the Ecorr value increases as the hydrophobicity of PVDF coating increases. These results showed that anti-corrosion property improves when the hydrophobicity of PVDF coating increases.