Polyurethane elastomers with novel soft segments containing a semifluorinated and 5,5-dimethylhydantoin pendant groups were prepared. These materials were used as polymeric surface modifiers (PSM) in conventional polyurethane coatings. The surface enrichment of the PSM was verified by Dynamic contact angle and XPS measurements. The PSM doped (2wt%) PU coating surface was activated by converting the near surface amide to chloramide using diluted hypochlorite solution. The biocidal activity of the surface against both Gram-positive and Gram-negative bacteria was demonstrated using a modified AATCC (American Association of Textile Chemists and Colorists) procedure. The wetting behavior of the novel PSM PU was opposite to the anticipated amphiphilic response: the surface became hydrophobic upon exposure to water. The term “contraphilic” was coined to describe this “strange” wetting pattern. An inter/intramolecular hydrogen bonding between the hydantoin moiety and the semifluorinated pendant groups was proposed for the hydrophilic (dry) state, when the surface is wetted water-amide hydrogen bonding takes place releasing the surface active semifluorinated group resulting hydrophobic (wet) state.