Self-Assembly in Multiferroic Nanocomposites

多铁性材料是指在同一化合物中同时具有磁有序性和电极化性的多功能材料。在这些材料中，电极化可以由磁场引起，反之亦然，磁化可以由电场引起，用于自旋电子器件、远程可切换器件、电容器、传感器和磁性数据存储。聚合物/纳米颗粒的纳米复合材料，通过将纳米颗粒并入聚合物基体中形成，由于相对于任一非杂化组分的潜在性能增强，已经收到了大量的研究兴趣。嵌段共聚物（BCP）作为基质的使用通过将纳米颗粒约束在所需的共聚物嵌段内而为控制纳米复合材料中纳米颗粒的空间和取向组织提供了前所未有的机会。基于BCP的纳米多铁性颗粒优先分离到目标BCP域的分级有序的新型纳米复合材料可以为开发具有可控介电常数和磁导率以及大磁电耦合的小型化多功能电磁材料和器件提供新的机会。这项研究的智力价值在于了解BCP/多铁性纳米颗粒纳米复合材料的自组装，这种复合材料建立在材料设计概念的基础上，并通过设计纳米复合材料中纳米颗粒的纳米级有序来控制多铁性。通过拟议的项目，将追求三个研究目标：（1）合成单分散的多铁性纳米颗粒，在表面上紧密和永久地修饰有明确的配体，为二嵌段共聚物（DBCP）中的一个嵌段提供化学亲和力;（2）组装纳米结构复合材料（即，纳米复合材料），将多铁性纳米颗粒结合在DBCP的目标块内;以及（3）根据电磁参数和成分的空间排列来评估纳米复合材料的铁电和铁磁特性以及磁电耦合。拟议工作的更广泛影响包括加强跨多个级别的纳米科学教育。将招募代表性不足的女本科生参与该研究项目。PI实验室的高中教师暑期研究将为将纳米材料科学知识转移到高中课堂提供媒介。高中女实习生将为全国5 - 8年级学生制定关于聚合物纳米材料和纳米晶体的网络课程计划。这项活动最终将使中小学生接触纳米世界。在DBCP纳米复合材料中采用多铁性纳米材料的意义体现在获得这些新型纳米结构材料的结构-性能关系的基础知识和专业知识。这类新材料可以在先进的自旋电子器件、电容器、致动器、换能器、传感器以及其他领域中实现广泛的应用，这些领域预计将满足民用应用和国家安全的关键需求（即，潜在的变革性研究），从而将基础科学发现转化为有益于社会的有用技术。

Abstract1159048Lin, ZhiqunMultiferroics are multifunctional materials that exhibit both magnetic order and electrical polarization in the same compound. In these materials, the electric polarization can be induced by a magnetic field and conversely, and the magnetization can be induced by an electric field for use in spintronic devices, remote switchable devices, capacitors, sensors, and magnetic data storage. Nanocomposites of polymer/nanoparticle, formed by incorporating nanoparticles into a polymer matrix, have received a great deal of research interest because of the potential performance enhancement relative to either of the non-hybrid constituents. The use of block copolymers (BCPs) as the matrix offers unprecedented opportunities for controlling the spatial and orientational organization of nanoparticles in nanocomposites by constraining the nanoparticles within desired block of copolymer. Crafting novel nanocomposites with hierarchical order based on BCPs with nanoscopic multiferroic particles preferentially segregated into the target BCP domains may offer new opportunities for developing miniaturized multifunctional electromagnetic materials and devices with controlled dielectric permittivity and magnetic permeability as well as large magnetoelectric coupling. This has yet to be explored.The intellectual merit of the proposed research is to understand the self-assembly in BCP/multiferroic nanoparticle nanocomposites that build on the materials-by-design concept and the control of multiferroic properties through engineering the nanometer-scale ordering of nanoparticles in the nanocomposites. Three research objectives will be pursued through the proposed project: (1) Synthesize monodispersed multiferroic nanoparticles intimately and permanently decorated with well-defined ligands at the surface that afford chemical affinity to one block in diblock copolymer (DBCP); (2) Assemble nanostructured composites (i.e., nanocomposites) with hierarchical order based on DBCPs, incorporating multiferroic nanoparticles within the target block of the DBCP; and (3) Evaluate the ferroelectric and ferromagnetic properties and magnetoelectric coupling of nanocomposites in terms of the electromagnetic parameters and spatial arrangement of constituents.The broader impacts of the proposed work include stronger nanoscience education across several levels. Underrepresented female undergraduate students will be recruited to participate in the research project. Summer research for high school teachers in the PI's lab will provide a medium for transferring nanomaterials science knowledge to high school classrooms. Web-based lesson plans on polymeric nanomaterials and nanocrystals will be developed by high-school female interns for 5th-8th graders nationwide. This activity will ultimately expose elementary and middle school students to the nano-world. The significance of employing multiferroic nanomaterials in DBCP nanocomposites is manifested in gaining fundamental knowledge and expertise on the structure-property relationships in these novel nanostructured materials. This new class of materials may promise a wide diversity of applications in advanced spintronics devices, capacitors, actuators, transducers, sensors, among other areas that are anticipated to fill a critical need in civilian applications and national security (i.e., potentially transformative research), thereby transitioning fundamental scientific discoveries into useful technologies that benefit society.