Major influence of the alkyl chain length of poly(2,4-dialkyl-3,4-propylenedioxythiophene) on the surface fibrous structures and hydrophobicity

Special Issue: From macromolecules to materials to systemsInternational audienceWe report the synthesis of 2,4-dialkyl-3,4-propylenedioxythiophene monomers with various alkyl chain length (n=1, 2, 3, 4, 5) and their use for the surface modification by electropolymerization. Surprisingly, a drastic decrease in surface hydrophobicity as the increase in the alkyl chain length between n = 2 and 3. The decrease is due to a change in the surface morphology from nanofibers to relatively smooth. Indeed, the increase in the alkyl chain length in the 2- and 4-positions induces very high steric hindrances during the polymerization. As a consequence, the oligomers formed in the first instances are smaller and as a consequence more soluble in solution, leading to smoother films. This work opens new strategies for the elaboration of highly hydrophobic PProDOT nanofibers for potential biological applications