Self-Assembly in Multiferroic Nanocomposites

1159048Lin、志群多铁化合物是一种在同一化合物中同时表现出磁序和电极化的多功能材料。在这些材料中，电极化可以由磁场感应，反之亦然，并且磁化可以由电场感应，用于自旋电子器件、远程可切换器件、电容器、传感器和磁数据存储。聚合物/纳米颗粒纳米复合材料是通过将纳米颗粒加入到聚合物基质中而形成的，由于相对于任何一种非杂化成分具有潜在的性能改善，因此受到了极大的研究兴趣。嵌段共聚物(BCP)的使用为控制纳米复合材料中纳米粒子的空间和取向组织提供了前所未有的机会，通过将纳米粒子限制在所需的共聚物嵌段内。基于BCP的新型层次化有序纳米复合材料的研究，为开发具有可控介电常数和磁导率以及大磁电耦合特性的小型化多功能电磁材料和器件提供了新的机遇。这一点还有待探索。拟议研究的智力价值在于了解BCP/多铁纳米颗粒纳米复合材料中的自组装，这种自组装建立在按设计材料概念的基础上，并通过设计纳米复合材料中纳米颗粒的纳米级有序化来控制多铁性能。通过拟议的项目将追求三个研究目标：(1)在两嵌段共聚物(DBCP)的表面紧密并永久地修饰具有良好定义的配体的单分散多铁纳米颗粒，使其与两嵌段共聚物(DBCP)中的一个嵌段具有化学亲和力；(2)基于DBCP组装具有层次结构的纳米复合材料(即纳米复合材料)，将多铁纳米颗粒加入DBCP的目标嵌段内；以及(3)从电磁参数和组成的空间排列来评估纳米复合材料的铁电和铁磁性能以及磁电耦合。这项研究项目将招募未被充分代表的女本科生参加。PI实验室为高中教师进行的暑期研究将提供一种将纳米材料科学知识转移到高中课堂的媒介。关于聚合物纳米材料和纳米晶体的网络课程计划将由高中女实习生为全国5-8年级的学生开发。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意义表现在获得了关于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、传感器等领域有广泛的应用前景，预计这些领域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.