Mechanical Constraints Enhance Electrical Energy Densities of Soft Dielectrics

Lin Zhang, Qiming Wang and Xuanhe Zhao*

 Applied Physics Letter, In press 

Abstract

            Dielectrics are essential components in modern electronics and electric systems. When a sufficiently high voltage is applied on a layer of a dielectric, the dielectric will breakdown electrically. The breakdown limits the electrical energy density of the dielectric. We show that constraining the deformation of soft dielectrics can greatly enhance their breakdown electric fields and thus increase their electrical energy densities.

Electro-creasing instability in deformed polymers: experiment and theory

Qiming Wang, Mukarram Tahir, Lin Zhang, and Xuanhe Zhao*

Soft Matter, In Press 

Abstract: Subjected to an electric field, a substrate-bonded polymer film develops a biaxial compressive stress parallel to the film. Once the electric field reaches a critical value, the initially flat surface of the polymer locally folds against itself to form a pattern of creases. We show that mechanical deformation of the polymer significantly affects the electro-creasing instability. Biaxially pre-stretching the polymer film before bonding to the substrate greatly increases the critical field for the instability, because the pre-stretch gives a biaxial tensile stress that counteracts the electric-field-induced compressive stress.