Two-phase material with surprising properties

Microstructure and macroscopic electro-mechanical properties are closely coupled in so-called ferroelectric polymers. An explanation for the high temperature dependence of this coupling has now been found at TU Wien. In certain materials, electrical and mechanical effects are closely linked: for example, the material may change its shape when an electrical field is applied or, conversely, an electrical field may be created when the material is deformed. Such electromechanically active materials are very important for many technical applications. Usually, such materials are special, inorganic crystals, which are hard and brittle. For this reason, so-called ferroelectric polymers are now being used. They are characterised by the fact that their polymer chains exist simultaneously in two different microstructures: some areas are strongly ordered (crystalline), while disordered (amorphous) areas form in between. These semicrystalline composites are electromechanically active and therefore combine electrical and mechanical effects, but at the same time they are also flexible and soft. At TU Wien, such materials have now been studied in detail - with surprising results: above a certain temperature, the properties change dramatically. A research team from TU Wien in cooperation with research groups from Madrid and London has now been able to explain why this happens. From micro-sensors to smart textiles