This collaborative research project concerns a combined theoretical and experimental investigation of interphases and their role in the enhancement of the macroscopic electromechanical response of dielectric elastomer nanoparticulate composites under finite deformations and finite electric fields. While the remarkable electromechanical properties of this emerging type of nanocomposites have been linked to interphasial phenomena around the nanoparticles, the precise (quantitative) nature of how the presence of interphases improves the macroscopic properties remains largely unresolved. Such a fundamental understanding is of utmost importance for advancing the technological exploitation of this promising class of materials as the next generation of actuators and sensors. The general mathematical framework developed will also be directly applicable to a wide range of other particulate reinforced composites. The project will train two graduate students for careers in academia or industry and will integrate research results in the undergraduate and graduate curricula at the University of Illinois Urbana-Champaign and the Pennsylvania State University. The PIs will also develop visual experiments illustrating the potential of dielectric elastomer nanoparticulate composites as the next generation of soft actuators to integrate into outreach to high schools.
The main objectives of the project are to: (i) obtain experimental measurements of the geometry, electromechanical properties, and space charge distribution in and around interphases in representative classes of dielectric elastomer nanoparticulate composites, (ii) derive and numerically implement a highly tractable homogenization framework to describe the effect of interphases containing space charges on the macroscopic electromechanical behavior of nanoparticulate composites, and (iii) deploy this framework to explore the design of nanoparticulate composites with optimally enhanced electrostriction capabilities. Objective (i) entails experiments covering nanoscopic to macroscopic length scales, while objective (ii) entails a generalized yet tractable definition of macrovariables capable to account for interphasial phenomena and its stable and convergent numerical implementation in the non-convex setting of finite deformations and finite electric fields.
