Effects of Corona treatment on electrical and mechanical properties of a porous dielectric elastomer

The main problem of dielectric elastomer (DE) actuators is today represented by the high driving electric fields (orders of 10-100 V/μm) necessary for their activation. Although several attempts have been made in order to increase strains by enhancing the dielectric constant (ε´) of such matrices and keeping low elastic moduli (Y) to control the ε/Y ratio, currently several challenges have still to be faced. In this work, a new approach is presented to enhance the electrical properties of DE elastomers. Soft elastomeric polyurethane (PU) matrices with foam structure were electrically modified via Corona process. Such matrices showed electret-like properties, possibly due to the presence of macro-dipoles established both at the matrix/pore surfaces and inside the bulk. Morphological (SEM, Bet), dielectric and dynamic-mechanical (DMA) analyses were performed in order to characterize the material. Results showed that Corona charging may represent a new promising route to obtain dielectric elastomers with improved dielectric properties, although ways to promote charge trapping and retention are still do be found.