高电驱动应变介电弹性体复合材料的设计、制备及性能研究

Dielectric elastomer actuator (DEA) that can transform the electrical energy into mechanical energy in response to applied electrical stimuli presents a novel and promising electromechanical transducer technology. Addition of conductive particles into a polymer matrix can increase the dielectric constant of dielectric elastomer composites obviously if the concentration of the conductive particles approaches the percolation threshold. However, there are usually accompanied by weak interfacial interactions, a significant increase in dielectric loss, a drastic reduction in electric breakdown strength, and a low actuated strain. In this work, the dielectric nanoparticles will be pre-deposited by poly(catechol/polyamine) (PCPA) layer and followed by grafting a second monomer with functional groups which can co-crosslink with elastomer matrix to form the core-shell structured dielectric nanoparticles. Then the core-shell structured dielectric nanoparticles will be introduced into the nitrile-butadiene rubber (NBR) matrix to prepare the dielectric elastomer composites. The surface characteristics of dielectric nanoparticles and crosslinking density of the elastomer matrix will be adjusted to obtain a high electromechanical sensitivity. The relationship among microstructure, intrinsic properties such as mechanical properties, viscoelasticity, dielectric properties, and insulating properties, and actuation properties such as effective compressive force, actuated strain, energy density, and electrical breakdown strength, will be systematically studied. In addition, the electromechanical coupling mechanism such as electromechanical coupling efficiency, electromechanical instability, electric breakdown failure, and charge leakage, will be studied. These will provide the theoretical foundation and technique method for designing and practical applications of high performance DEA, along with a new approach for developing “artificial muscles”.

介电弹性体驱动器(DEA)在电场作用下能将电能转变为机械能，有望成为新一代电-机传感器。导电填料掺杂型介电弹性体复合材料虽然在导电填料浓度接近逾渗阈值时可获得较大介电常数，但存在界面作用弱、介电损耗高、电击穿强度低及电驱动应变小的缺点。为解决上述问题，本项目拟采用低成本聚(邻苯二酚/多胺)修饰及二次功能化对导电聚合物纳米粒子进行表面改性，引入绝缘层和可与橡胶共交联的基团，填充至丁腈橡胶中，通过调控介电纳米粒子的表面性质及弹性体基体的交联密度制备出高驱动敏感因子介电弹性体复合材料。拟建立介电弹性体复合材料微观结构及其本征性能(力学性能、粘弹性能、介电性能、绝缘性能)与电驱动性能(有效压缩力、电驱动应变、能量密度、电击穿强度)间关系，探讨电-机耦合机制(电-机耦合效率、电-机失稳、电击穿失效、电荷泄露)，为高性能DEA的设计和应用提供理论依据和方法，可望为“人工肌肉”的开发提供新的途径。

介电弹性体驱动器(DEAs)能在电场刺激下将电能转变为机械能，被誉为“人工肌肉”，有望成为新一代微驱动器，可广泛应用于假肢器官、医学修复、盲文显示等生物医疗领域。但是DEA需施加高驱动电场(高达150kV/mm)才能产生较大电驱动应变，一旦发生电击穿或漏电，对人体和设备将造成很大伤害。制备驱动性能稳定、安全可靠、可实际应用的DEA成为微驱动器领域研究和开发的关键。本项目工作主要集中在改善介电填料与弹性体基体间界面性能，以提高介电弹性体复合材料的电驱动性能和导热性能。具体研究内容包括：(1)通过表面修饰及二次功能化构筑核壳结构介电粒子，制备出高电驱动敏感因子介电弹性体复合材料；(2)利用介电填料与极性增塑剂间协同效应，制备低弹性模量介电弹性体复合材料，实现其低驱动电场下的高驱动应变；(3)将无机导热粒子与导电材料自组装，构筑异质结功能填料，制备兼顾高介电和高导热弹性体复合材料。通过本项目的研究，建立了介电弹性体复合材料的微观结构与电驱动性能间响应关系，并初步阐明机-电耦合机制，为高性能DEA的设计制备及实际应用提供理论基础和方法，具有重要的学术价值和理论意义。