Directing Self-Assembly of Liquid Crystalline Block Co-Oligomers in Combined Optical and Magnetic Fields

材料科学家试图了解材料的特性是如何与其结构相关联的，并开发方法来创造实现所需特性所需的结构。传统上，科学家们关注的是原子和分子的排列结构，这是由材料的化学成分自然产生的。然而，近年来的新研究表明，使用人造或合成材料结构可以实现新颖且通常意想不到的性能。该项目旨在创造聚合物材料的光学和机械性能的可编程空间变化，作为实现可产生有用性能的合成结构的新途径。这个项目的目标将通过基础研究来推进，这些研究将检验设计的光响应聚合物的光驱动结构转变和这种聚合物的磁场响应。合成结构将通过使用空间控制的动态光照射与磁场相结合来开发。该项目解决了聚合物中光学驱动结构转变的基本知识缺口，以及在此类系统中易于创建属性空间变化的处理方法。控制属性的空间变化为材料功能的编程提供了一条途径，并在各种能源和微电子相关应用中得到了寻求。因此，考虑到这些部门新材料的发展，预计该项目将产生更广泛的影响。该项目涉及一系列额外的更广泛的影响，包括新的K-12外展计划，课程的发展，重点招募不同的研究人员，以及本科生研究人员的参与。控制自组装聚合物的结构顺序仍然是材料科学家研究的一个至关重要的焦点。光场的时空控制与磁场相结合，可以提供一种高度通用的处理此类材料的方法。在这种情况下，迫切需要理解和设计可光切换有序自组装聚合物，并开发利用光场引导自组装的新模式。本项目主要研究光开关液晶嵌段共聚物（LC BCOs）的分子设计和表征，以及利用光场和光场结合控制其结构顺序的策略。这些系统为探索光场存在下的有序跃迁，以及利用光场与磁场协同作用开发定向自组装的新模式提供了丰富的前景。提出的工作针对这些机会，总体上面向开发新材料和理解它们的结构-性质关系，并利用光响应排序来实现新的，更通用的定向自组装模式。具体目标是：1。阐明LC BCOs及其混合物的相行为和光驱动有序[j]。创建由空间变化的光学场编程的空间变化纹理3。发展结合光和磁场处理的知识价值源于系统地探索自组装和一种仍在出现的大分子的相行为，并实现了迄今为止难以捉摸的定向自组装的通用模式。如果成功实施，这项工作将为利用光场操纵LC BCOs中的有效相互作用提供重要见解，并将以前所未有的保真度实现复杂的空间变化纹理。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYMaterials scientists seek to understand how the properties of materials are related to their structure and to develop methods to create the structures needed to achieve desired properties. Traditionally, scientists have focused on structure in terms of the arrangement of atoms and molecules that result naturally from the chemical composition of a material. However, in recent years new research has demonstrated that novel and often unanticipated properties can be realized by using human-made or synthetic material structures. This project aims to enable the creation of programmed spatial variation of optical and mechanical properties in polymeric materials as a new route to realize synthetic structures that can give rise to useful properties. This project aim will be advanced by fundamental studies that examine optically-driven structural transitions in designed light-responsive polymers and the magnetic field response of such polymers. Synthetic structures will be developed by the use of spatially-controlled dynamic light exposure in concert with magnetic fields. This project addresses a fundamental knowledge-gap regarding optically driven structural transitions in polymers, and processing methodologies to readily create spatial variation of properties in such systems. Controlling the spatial variation of properties provides a route for programming material function, and is sought in a variety of energy and microelectronics-related applications. It is therefore anticipated that this project will have broader impacts given the implications for the development of new materials in these sectors. This project involves a range of additional broader impacts including a new K-12 outreach program, the development of curriculum, a focus on recruiting diverse researchers, and the involvement of undergraduate researchers.TECHNICAL SUMMARYControlling structural order in self-assembled polymers remains a critically important focus of research for materials scientists. Spatio-temporal control of optical fields, in concert with magnetic fields, could provide a highly versatile means of processing such materials. In this context, there is a critical need to understand and engineer photoswitchable ordering self-assembling polymers, and to develop new modalities for guiding self-assembly using optical fields. This project is centered on molecular design and characterization of photoswitchable liquid crystalline block co-oligomers (LC BCOs), and the development of strategies for controlling their structural order using optical fields, and optical fields in combination with magnetic fields. These systems provide a rich landscape in which to explore ordering transitions in the presence of optical fields, and in which to develop new modes of directed self-assembly using optical fields in concert with magnetic fields. The proposed work targets these opportunities and is geared overall towards developing new materials and understanding their structure-property relationships, and leveraging photo-responsive ordering to realize new, more versatile, modalities for directed self-assembly. The specific objectives are:1. Elucidate phase behavior and photo-driven ordering in LC BCOs and their blends2. Create spatially-varying textures programmed by spatially-varying optical fields3. Develop combined optical and magnetic field processingThe intellectual merit stems from the systematic exploration of self-assembly and phase behavior of a still emerging class of macromolecules, and the realization of a versatile modality for directed self-assembly that has been elusive to date. Successfully executed, the proposed work will provide critical insight regarding the manipulation of effective interactions in LC BCOs using optical fields and will enable the realization of complex spatially varying textures with unprecedented fidelity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.