Self-Assembly in Multiferroic Nanocomposites

【摘要】多铁质材料是在同一化合物中同时具有磁有序和电极化的多功能材料。在这些材料中，电极化可以由磁场诱导，反之，磁化可以由电场诱导，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/纳米颗粒纳米复合材料是通过将纳米颗粒掺入聚合物基体而形成的，由于其相对于任何一种非杂化成分具有潜在的性能增强，因此受到了广泛的研究兴趣。嵌段共聚物（bcp）作为基体的使用，通过将纳米颗粒限制在所需的共聚物嵌段内，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。利用纳米级多铁粒子优先分离到目标BCP域，制备基于BCP的新型有序纳米复合材料，可能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。这一点还有待探索。本研究的智力价值在于理解BCP/多铁性纳米颗粒复合材料的自组装，该复合材料基于材料设计概念，并通过工程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。通过该项目将实现三个研究目标：(1)合成单分散的多铁纳米颗粒，并在表面与二嵌段共聚物（DBCP）中的一个嵌段具有化学亲和力的明确定义的配体密切和永久修饰；(2)基于DBCP的层次顺序组装纳米结构复合材料（即纳米复合材料），在DBCP的目标块内加入多铁纳米颗粒；(3)从电磁参数和组分的空间排列角度评价纳米复合材料的铁电、铁磁性能和磁电耦合。提议的工作的更广泛的影响包括在几个层面上加强纳米科学教育。被低估的女本科生将被招募参与研究项目。在PI实验室为高中教师进行的暑期研究将为将纳米材料科学知识转移到高中课堂提供一种媒介。基于网络的高分子纳米材料和纳米晶体课程计划将由高中女实习生为全国5 -8年级学生制定。这项活动最终将使中小学生接触到纳米世界。在DBCP纳米复合材料中使用多铁纳米材料的重要性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。这种新型材料有望在先进的自旋电子器件、电容器、致动器、换能器、传感器等领域得到广泛的应用，有望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.