Design, Manufacturing and Optimization of Ferroelectric Polymer Based Nanocomposite Films Using Langmuir-Blodgett Deposition

纳米结构的铁电体被设想为具有新颖和优越的功能特性，然而钙钛矿明显存在失去铁电性的尺寸限制，严重限制了铁电纳米结构的发展。为了克服这一困难，本项目寻求利用Langmuir-Blodgett （LB）沉积技术开发新型铁电聚合物基纳米复合薄膜。多层复合薄膜将在纳米尺度上由铁电聚合物薄膜与其他介质或铁电层交替形成，这些介质或铁电层是通过包括标准溶剂沉积和纳米颗粒分散技术在内的各种方法制成的。平面内纳米结构将基于LB膜中正负纳米模板的形成而构建，纳米颗粒将丝网印刷到纳米片之间或纳米孔中的衬底上。因此，具有一、二、三维非均质性的铁电纳米复合薄膜将被制备出来。制造过程将与我们的建模工作紧密结合，其中铁电纳米复合材料的微观结构演变将通过能量最小化方法和相场理论进行模拟，并通过微观力学模型分析其宏观性能。结构-性能关系的建模将导致一系列功能性能的优化方案，包括电伸缩和压电效应，热释电系数和介电可调性，这将用于指导纳米结构铁电器件的加工和制造。从这项研究中获得的知识将使铁电聚合物基纳米复合薄膜的设计和优化具有新颖和独特的功能特性，对微传感器和微致动器、红外探测器和微波器件等纳米结构铁电器件的制造产生直接影响。该项目将为两名研究生提供机会，参与纳米结构铁电聚合物薄膜的建模、制造和表征的跨学科研究。它还将通过内布拉斯加大学林肯分校的本科生创造性活动和研究体验项目（UCARE），通过铁电纳米复合材料的设计、制造和表征之间的独特互动，吸引本科生进入科学和工程领域。这项研究的结果将被纳入PI开发的活性材料课程的内容，该课程目前只涉及体铁电行为。还将开发互动式网络教程和数据库，以确保广泛传播我们的科学和技术发现。

Nanostructured ferroelectrics are envisioned to possess novel and superior functional properties, yet the apparent existence of a size limit under which perovskites lose ferroelectricity severely limits the development of ferroelectric nanostructures. To overcome the difficulty, this project seeks to develop novel ferroelectric polymer based nanocomposite films using Langmuir-Blodgett (LB) deposition. The multilayer composite films will be built up by alternating at nanoscale the ferroelectric polymer films with other dielectric or ferroelectric layers made by various methods including standard solvent-deposition and nanoparticle dispersion techniques. The in-plane nanostructures will be constructed based on the formation of positive and negative nanomesa templates in LB films, with nanoparticles screen printed onto the substrate between the nanomesas or in the nanoholes. As such, ferroelectric nanocomposite films with one-, two- and three-dimensional heterogeneity will be fabricated. The fabrication will be tightly coupled with our modeling effort, where the microstructure evolution in ferroelectric nanocomposites will be simulated by energy-minimization approach and phase field theory, and their macroscopic properties will be analyzed by micromechanics models. The modeling of structure-property relationship will lead to an optimization scheme for a series of functional properties, including electrostriction and piezoelectric effect, pyroelectric coefficients, and dielectric tunability, which will be applied to guide the processing and fabrication of nanostructured ferroelectric devices.The knowledge derived from this research will enable the design and optimization of ferroelectric polymer based nanocomposite films possessing novel and unique functional properties, with direct impact on the manufacturing of nanostructured ferroelectric devices such as microsensors and microactuators, infrared detectors and microwave devices. The project will provide the opportunity to two graduate students to get involved in the interdisciplinary research dealing with the modeling, fabrication, and characterization of nanostructured ferroelectric polymer films. It will also draw undergraduates into science and engineering via the unique interaction between design, manufacturing, and characterization of ferroelectric nanocomposites through the Undergraduate Creative Activities & Research Experiences program (UCARE) at University of Nebraska-Lincoln. Results from this research will be incroporated in the content of an active materials course developed by the PI, which currently addreses only bulk ferroelectric behavior. Interactive, web-based tutorials and database will also be devoped to ensure broad dissemination of our scientific and technological finding.