Flexible and lightweight electrodes are prepared using a two-step process. First, poly(3,4ethylenedioxythiophene) (PEDOT) microparticles are loaded into poly-γ-glutamic acid (γ-PGA) hydrogel matrix, during the reaction of the biopolymer chains with the cross-linker, cystamine. After this, PEDOT particles dispersed inside the hydrogel are used as polymerization nuclei for the chronoamperometric synthesis of poly(hydroxymethyl-3,4-ethylenedioxythiophene) (PHMeDOT) in aqueous solution. After characterization of the resulting electrode composites, electrochemical studies revealed that the capacitive properties drastically depend on the polymerization time used to produce PHMeDOT inside the loaded hydrogel matrix. Specifically, flexible electrodes obtained using a polymerization time of 7 hours exhibit an specific capacitance of 45.40.7 mF/cm 2 from cyclic voltammetry and charge-discharge long-term stability. The applicability of these electrodes in lightweight and flexible energy-harvesting systems useful for energy-autonomous, low-power, disposable electronic devices, has been proved powering a LED bulb.

Composites formed by poly (3,4-ethylenedioxythiophene) and alumina (PEDOT/Al 2 O 3 ) have been prepared by in situ anodic polymerization. For this purpose, the stability of 1:1 and 4:1 monomer:alumina aqueous solutions has been examined as a function of the pH (2.3, 4.0, 7.0, 8.8 or 10.8). Results indicate that the monomer behaves as a dispersant that remains stable at the studied basic pHs despite they are close to the isoelectric point of alumina. Although the thermal stability of the composites is considerably affected by the pH of the reaction medium, its influence on the surface morphology is very small. Independently of the synthetic conditions, the electrochemical properties were better for PEDOT/Al 2 O 3 than for pure PEDOT, reflecting that alumina particles promote the charge mobility. The highest specific capacitance (141 F/g), which was 55% higher than that obtained for pure PEDOT, was achieved for the composite prepared at pH= 8.8 using a 4:1 monomer:alumina ratio.These conditions favour the participation of OH -groups as secondary doping agents without degrading the polymer matrix and enhance the specific surface of the films, facilitating the ionic mobility. On the other hand, application of a multi-step polymerization strategy has shown that interfaces originated by consecutive steps enhance the specific capacitance.