Mireille Tixier (LMV) - Constitutive equations of an ionic electroactive polymer

Ionic electroactive polymers (EAPs) have the ability to deform under the action of an electric field, so
they can be used as actuators or sensors; which gives them very promising applications such as the
design of micro-pumps, micro-actuators or micro-robots, artificial muscles, flapping wings
(biomimetic), energy harvesting systems.... We first focused on an ionic polymer-metal composite
(IPMC) consisting of a film of ionic polymer saturated with water and metalized on both sides, and
then on a pseudo trilayer based on a semiconductor polymer saturated with an ionic liquid. When an
electric field is applied, the cations move towards the negative electrode, making it swell, while the
volume decreases on the opposite side; this results in the bending of the strip. Conversely, the
deflection of the film generates a potential difference between the electrodes. This system is
assimilated to a continuous deformable porous medium in which flows an ionic solution. We wrote its
balance equations and thermodynamic relations. The thermodynamics of linear irreversible processes
then provided its constitutive relations. The modeling is validated in the static isothermal case by
applying it to a cantilevered blade subject to a continuous potential difference between its two faces.
The results obtained are in good agreement with the experimental data published in the literature.