Synthesis of Janus Hybrid Nanoparticles as Colloidal Amphiphiles

技术概要：将研究一类新型混合胶体的合成、组装和聚合，该胶体由具有不同胶体成分的不对称纳米棒和差异功能化聚合物配体组成。 这些类型的混合胶体将表现出Janus型结构特征，因为无机胶体相将由与单个偶极钴纳米颗粒（CoNP）缀合的单个半导体纳米棒（基于CdSe@CdS）组成。 此外，将实现具有（共）聚合物配体的CdSe@CdS纳米棒和CoNP表面的可控官能化。 这种Janus纳米颗粒是一种新颖且独特的平台，其能够用不同类型的聚合物配体选择性和差异性地官能化CoNP和CdSeOCdS纳米棒表面，所述聚合物配体由具有不同亲水性的受控自由基聚合制成，从而能够产生胶体两亲性纳米材料。 胶体和聚合物组分的合成和结构变化将是研究的中心焦点，这将使进一步研究这些Janus NP的组装和通过胶体聚合转化为异质结构光催化材料。 PI将研究这些两亲性Janus NP在溶液中和油-水界面处的自组织，以形成各种胶体组装体，目标是形成具有横向取向的纳米棒的线性NP链。 然后进行Janus NP胶体组装体的金属CoNP相的氧化，以提供沿着钴氧化物主链的每个重复单元沿着携带CdSe@CdS纳米棒侧链的钴氧化物纳米线。 这种方法提供了一种途径，空间和电子有序的p-n半导体结，能量对准的光刻。这些纳米材料的组成，形态和电子结构将通过TEM，XRD，光电子和光学光谱学，沿着与Janus NP胶体组装和溶液光学探针分子照射后的电子显微镜研究进行研究。 非技术总结：拟议的研究旨在开发新方法来制备新型材料，该材料将联合收割机有机聚合物和无机颗粒结合在一起，并控制不同组分的尺寸、形状和功能。 这将需要开发新的合成化学来制备这些类型的尺寸非常小的无机颗粒（即，纳米级的），并用有机聚合物配体的壳作为塑料涂层进行装饰。 由于这些类型的构建块非常新颖，因此缺乏将它们制备和杂交成单一有用材料的方法，而这正是拟议研究的目的。 因此，这项研究是高度跨学科的，但以基础和基础聚合物科学为基础。 在这些合成方法的开发之后，不对称纳米颗粒的制备将使得能够评估这些材料的能量相关问题，例如从水中光催化产生氢。 此外，将通过联合指导项目和PI提供的一系列讲座，将研究与K-12学生的教育活动相结合。 与韩国学术机构（首尔国立大学）的合作也将通过联合技术研究和教育活动纳入该项目。

TECHNICAL SUMMARY: The synthesis, assembly and polymerization of a new class of hybrid colloids composed of asymmetric nanorods with disparate colloidal components and differentially functionalized polymer ligands will be pursued. These types of hybrid colloids will exhibit Janus-type structural character, as the inorganic colloidal phase will be composed of a single semiconductor nanorod (based on CdSe@CdS) conjugated to a single dipolar cobalt nanoparticle (CoNP). Furthermore, the controllable functionalization of CdSe@CdS nanorod and CoNP surfaces with (co)polymeric ligands will be achieved. This Janus nanoparticle is a novel and unique platform that enables selective and differential functionalization of CoNP and CdSe@CdS nanorod surfaces with different types of polymeric ligands made from controlled radical polymerizations of varying hydrophilicity enabling creation of colloidal amphiphilic nanomaterials. The synthesis and structural variation of colloidal and polymeric components will be the central focus of the research that will enable further studies on the assembly of these Janus NPs and conversion via colloidal polymerization into heterostructured photocatalytic materials. The PI will investigate the self-organization of these amphiphilic Janus NP in solution and at oil-water interfaces to form various colloidal assemblies targeting the formation of linear NP chains with nanorods laterally oriented. Oxidation of the metallic CoNP phases of the Janus NP colloidal assemblies will then be conducted to afford cobalt oxide nanowires carrying CdSe@CdS nanorod side chains along every repeating unit of the cobalt oxide backbone. This methodology affords a route to spatially and electronically ordered p-n semiconductor junctions that are energetically aligned for photocatalysis. The composition, morphology, and electronic structure of these nanomaterials will be investigated via TEM, XRD, photoelectron and optical spectroscopies, along with photocatalysis studies with Janus NP colloidal assemblies and solution optical probe molecules upon irradiation. NON-TECHNICAL SUMMARY:The proposed research aims to develop new methods to prepare novel materials that combine organic polymers and inorganic particles with control of size, shape and function of the different components. This will require the development of new synthetic chemistry to prepare these types of inorganic particles that will be very small in size (i.e., nanoscopic) and decorated with a shell of organic polymer ligands as a plastic coating. Because these types of building blocks are very novel, methods to prepare and hybridize these into a single useful material are lacking, which the proposed research aims to address. Hence, the research is highly interdisciplinary, but grounded in basic and fundamental polymer science. Upon development of these synthetic methods, the preparation of asymmetric nanoparticles will enable evaluation of these materials for energy related problems, such as, photocatalytic generation of hydrogen from water. Furthermore, integration of the research with educational activities with K-12 students will be achieved by joint mentoring projects and a series of lectures given by the PI. Collaborations with South Korean academic institutions (Seoul National University) will also be integrated into this project through joint technical research and educational activities.