| Summary: | 碩士 === 中原大學 === 化學工程研究所 === 95 === Super-hydrophobic and oleophobic polypropylene (PP) surfaces were prepared by surface plasma modification using tetrafluoromethane (CF4) plasma. The characteristics of surface were investigated by means of contact angle measurement, scanning electron microscopy, atomic force microscopy, X-ray diffraction (XRD) and electron spectroscopy for chemical analysis.
First, the PP sheet surface showed super-hydrophobicity (~150∘)
and oleophobicity (~120∘) after CF4 plasma modification, and analysis results reveal that the modified surface showed roughness enhancement and PTFE-like composition. To investigate the relation between surface roughness and water contact angle measurement, both Wenzel and Cassie-Baxter models were used. It was found that the behavior of water droplet on PP surface is close to Cassie-Baxter model. The untreated PP sheet have crystalline structure examined by XRD, it seems that the enhancement of surface roughness were based on the different etching rates between crystalline and amorphous materials.
Secondly, PP sheet was modified by argon and oxygen plasma, and the surface roughness is much less than that treated by CF4 plasma. It seems that surface fluorination was helpful to enhance the selectivity of etch rate between crystalline and amorphous materials. And oleophobicity of surface was not enhanced after argon or oxygen plasma modification.
By using remote CF4 plasma modification, the characteristics of PP sheet surface such as contact angle and surface roughness show decreased trend and the surface F/C ratio shows increased then decreased trend when leaving from plasma region. It reveals that ion bombardment is helpful for surface roughness enhancement.
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