Influence of Ionic and Electronic Transport on the Rheology of Shape Changing Polymeric Materials

Within the project, mixed conductors (e.g., PEDOT:PSS) will be rheologically analyzed through combined uniaxial and torsional experiments. Complex shear and Young’s moduli will be recorded as functions of applied electrical field, temperature and water/electrolyte uptake. The characterization of samples and devices on the scale of millimeters to centimeters will facilitate the investigation of evolving effective elastic moduli (Young’s modulus E and shear modulus G) in harmonic tension and torsion tests while the doping state of the material will be controlled. The coupling of electrical and ionic conductivity with mechanical deformations shall be investigated and volume changes of the material depending on the applied electric field and doping state will be characterized in relation to evolving eigenstrains and eigenstresses. Furthermore, the inverse coupling effect of mechanical actuation on the resulting electronic conductivity is of key interest. The goal is to better understand and predict the emerging rheological properties such as glass transition temperature TG, mechanical relaxation times and materials dissipation of mixed conducting polymers, which have a huge impact on the applicability of these material systems including actuators.