Here, a bioinspired strategy is used to prepare well-ordered nanotubular structures, as observed in animals and plants, such as gecko toe pads or corals. The nanotubes are obtained by templateless electropolymerization of thieno[3,4- b ]thiophene-based monomers with various aromatic groups in an organic solvent (dichloromethane). The most interesting and robust structures were obtained with carbazole and pyrene substituents to the base monomer structure, since these groups participate significantly in the polymerization and also have strong π -stacking interactions. The addition of water to electropolymerization solvent significantly impacted the formation of nanotubes, as it caused the release of a significant amount of H 2 and O 2 bubbles, depending on the electropolymerization method. Identifying templateless approaches to vary nanotubular structures is very interesting, as these materials are sought-after for applications in water harvesting systems. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 3)’.

The bioinspiration is one of the best ways to make a breakthrough in a field, and particularly in the wetting properties. Bioinspired by natural species such as rose petals and gecko foot and previous researches, nanotubular structures are prepared here by soft-template electropolymerization in organic solvent and using an original benzotrithiophene with a hydrophilic carboxyl group, as the monomer. The best results are obtained by cyclic voltammetry because of a much higher amount of gas bubbles released with this deposition method. Both nanoparticles and nanotubes are observed while the water content has an influence on the number of nanotubes. Even if the monomer has hydrophilic carboxyl group, the best films have both high hydrophobicity (apparent water contact angle up to 130.7°) and strong water adhesion (petal effect). These surfaces could be used in the future in applications such as water harvesting systems.

Controlling the shape of surface nanostructures is fundamental for various potential applications for example, in water harvesting systems, liquid transportation or oil/water separation membranes. Here, the creation of porous surface structures is made by a process called templateless electropolymerization, in which water (H2O) is oxidized/reduced to form gas (O2/H2) bubbles onto the surfaces and acting as soft template for the polymer growth.Keeping the monomer (thieno[3,4-b]thiophene) and the substituent (pyrene) constant, we demonstrate how a flexible PEG spacer can affect the structure shape. Here, when the PEG spacer increases, the structures change from nanotubes (1D growth), to nanoribbons (2D) and after to hollow nanospheres (3D), which also affects the wetting properties.