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Effect of side chain length on the molecular aggregation states and surface properties of poly(fluoroalkyl acrylate)s [PFA-Cy, where y is fluoromethylene number in Rf group] thin films were systematically investigated. Spin-coated PFA-Cy thin films were characterized by static and dynamic contact angle measurements, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry, wide-angle X-ray diffraction(WAXD) and grazing- incidence WAXD(GIWAXD). The receding contact angles showed small values for PFA-Cy with short side chain (y≤6) and increased above y≥8. WAXD and GIWAXD revealed that fluoroalkyl side chain of PFA-Cy with y≥8 was crystallized and formed ordered structures at the surface region as well as bulk one. These results suggest that water repellent mechanism of PFA-Cy can be attributed to the presence of highly ordered fluoroalkyl side chains at the outermost surfaces. The results of XPS in the dry and hydrated states and contact angle measurement in water support the mechanism of lowering contact angle for water by exposure of carbonyl group to the water interface through reorientation of short fluoroalkyl chains. The surface nanotexture was formed on PFA-C8 through imprinting of anodic aluminum oxide films with pore diameter of 200nm. This nano-imprinted surface showed extremely high hydrophobicity as well as high oleophobicity. |