Simultaneous electropolymerization of pyrrole and anionic or cationic polymerizable monomeric ionic liquids. Linear actuation of the attained materials

Abstract

The simultaneous galvanostatic electrogeneration of polypyrrole (PPy) and a polyanion, or a polycation, from the concomitant solutions of pyrrole and monomeric ionic liquids (PIL) give films of two interpenetrated polymeric networks: polyanion-PPy (PILA-PPy) and polycation-PPy (PILC-PPy), as corroborated by Fourier transform infrared (FTIR) spectroscopy. The linear actuation was characterized by cyclic voltammetry and chronoamperometry in aqueous electrolyte describing cation-driven actuation of the PILA-PPy actuators (cation exchange during oxidation/reduction) and anion-driven actuation of the PILC-PPy actuation. The exchange of a unique ion in each actuator, corroborated by energy dispersive X-ray (EDX) analysis of the oxidized and reduced materials, allows the control of the actuation direction. The concomitant driving electrochemical reactions are described. Coulovoltammetric responses present a closed loop in the studied potential range indicating that only those reactions (oxidation/reduction) are present in the studied potential range (0.65 V and − 0.6 V). The PILC-PPy strain was 8.7% and the stress gradient 1.45 MPa, overcoming 1.5 times those from PILA-PPy actuators, consuming also a higher charge density, having 2.1 times better conductivity and 1.3 times higher diffusion-coefficients. The stability of the actuators was studied by consecutive cycling. The PILA-PPy and PILC-PPy films are characterized by scanning electron microscopy (SEM), FTIR and EDX spectroscopy.