Electrochimica Acta, Vol.269, 462-478, 2018
Nanocups and hollow microspheres formed by a one-step and templateless electropolymerization of thieno[3,4-b]thiophene derivatives as a function of the substituent
Here we show a one-step and templateless approach to design nanocups and hollow microspheres structures by an electrochemical polymerization. Monomers derived from thieno[3,4-b]thiophene bearing linear, branched and aromatic substituents were successfully synthesized by a two-step synthetic route and electropolymerized yielding unique surface structures. First, we show the versatility of the thienothiophenes monomers to create different structures on the surfaces. More precisely, branched alkyl chains derivatives (Th-Br-n) are efficient to prepare densely packed hollow microspheres with different particle sizes. By contrast, aromatic substituents such as naphthyl groups (Th-Na) lead to vertically aligned nanocups. The mechanism of structure formation is direct related to the pi-pi stacking interaction between the molecules which drive a unidimensional growth with Th-Na yielding cups and a tridimensional growth with Th-Br-n yielding spheres during the electropolymerization. Since the process to obtain nanotubes is rare in the literature, the formation of nanotubular structures is evaluated using two different electrochemical methods: cyclic voltammetry and constant potential. The amount of gas (O-2 and/or H-2 as a function of the electrodeposition method) produced from trace water during the electropolymerization is crucial on the formation of porous structures. The growth of the larger nanocups is favored by cyclic voltammetry but their number is less important than at constant potential. Moreover, while parahydrophobic properties were obtained for all the families by cyclic voltammetry, hydrophilic surfaces were produced at constant potential. This first work showed the monomers synthesis, electrochemical polymerization and surface characterization of various thieno[3,4-b] thiophene derivatives for a potential application on surface science as in water transport and membrane design, for example. (C) 2018 Elsevier Ltd. All rights reserved.