Synthesis, characterization and surface wettability of polythiophene derivatives containing semi-fluorinated liquid-crystalline segment

Abstract

In the scope of increasing our knowledge on the elaboration of smart surfaces, the aim of this work was to synthesize monomers as starting materials for the polymerization or copolymerization via electrochemical route. We report the synthesis and characterization of original structures containing a single phenyl unit bound, on one side, to a semi-fluorinated tail via a thioester connector and, on the other side, to a thiophene moiety. This design approach using cheap raw materials (a single phenyl ring as mesogenic core) associated to an electropolymerizable unit is of great interest in the development of liquid crystal low cost materials to build-up non-wetting surfaces based on the fluorophobic effect. The mesomorphic properties were characterized using differential scanning calorimetry and optical polarizing microscopy. The effect of the length of the fluorinated tail induced the formation of a smectic enantiotropic mesophase for F-hexyl and F-octyl tails. The polymerization of the films was performed in solution of sodium perchlorate in acetonitrile. Hydrophobic surfaces were obtained from the monomers containing a F-hexyl and F-octyl tail, while superhydrophobic surfaces (contact angle of water of 158°) were reached from the monomer containing a F-butyl tail.