fig1

Figure 1. Electrodeposition of core-shell structures. (A) Chemical reactions involved in electropolymerisation (1) of EDOT to neutral state of PEDOT (benzoid structure, top) and redox equilibrium (blue block) to oxidized PEDOT (quinoid structure, bipolaron represented in blue, bottom) followed by (2) decomposition of calcium carbonate; and (3) complexation with alginate macromolecules representing the alginate hydrogel formation (green block). (B) Schematic representation of the 3-electrode electrochemical cell with reference electrode (RE), working electrode (WE) and counter electrode (CE). On the left, coaxial representation (red dashed square) of the core-shell structures deposited over gold wire. On the right, schematic representation (blue) of molecules and ionic species present in the bulk electrolyte, above the critical micellar concentration (CMC) and WE potential of +1.4 V (vs. Ag/AgCl/KCl 3M). The respective order of chemical reactions (1-3) leading to core-shell formation is indicated. (C) Photograph of the PEDOT/alginate structures electrodeposited over a gold wire, followed by SEM images of the alginate shell surface (middle) and PEDOT core layer (right). (D) SEM image (left) of a cross section at the PEDOT/alginate interface and atomic distribution (right) of sulphur (S, Kα1 in red) and calcium (Ca, Kα1 in green).