Collaborative Research: Extreme Enhancement of the Electromechanical Properties of Soft Nano-Particulate Composites via Interphases

这项合作研究项目涉及介电弹性体纳米颗粒复合材料在有限变形和有限电场下的介电相及其在增强宏观机电响应中的作用的理论和实验相结合的研究。虽然这种新兴类型的纳米复合材料的显著机电性能与纳米颗粒周围的相间现象有关，但界面相的存在如何改善宏观性能的精确(定量)本质在很大程度上仍未解决。这种基本的理解对于推动这种有希望的材料作为下一代执行器和传感器的技术开发是至关重要的。所开发的通用数学框架也将直接适用于广泛的其他颗粒增强复合材料。该项目将培养两名在学术界或工业界就业的研究生，并将把研究成果纳入伊利诺伊大学厄巴纳-香槟分校和宾夕法尼亚州立大学的本科生和研究生课程。PIS还将开发可视化实验，展示介电弹性体纳米颗粒复合材料作为下一代软致动器的潜力，以整合到高中。该项目的主要目标是：(I)获得具有代表性的介电弹性体纳米颗粒复合材料中间相及其周围的几何形状、机电性能和空间电荷分布的实验测量，(Ii)推导并数值实现一个高度可处理的均匀框架，以描述含有空间电荷的中间相对纳米颗粒复合材料宏观机电行为的影响，以及(Iii)应用该框架来探索具有最佳电致伸缩能力的纳米颗粒复合材料的设计。目标(I)需要从纳米到宏观长度尺度的实验，而目标(II)需要能够解释相间现象的宏观变量的广义但易处理的定义，以及在有限变形和有限电场的非凸设置下的稳定和收敛的数值实现。

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.