CAREER: Photocatalytic Optical Fibers

由于光可以自由收集或高效产生，用光而不是热来驱动化学转化可以比传统的化学生产方法具有显著的优势。然而，在将这些主要是学术上的发现推广到工业采用所需的规模方面仍然存在挑战，限制了更安全、更温和的化学加工条件对社会的好处。限制光化学过程规模化的一个重要因素是，尽管原料的高吸光系数是反应效率的必要条件，但它也限制了光对反应介质的穿透深度。常用的光催化剂也可能贵得令人望而却步，而且最终产品中残留的催化剂杂质往往会导致变色或降解。为了解决这些限制，这个职业项目将研究使用涂有光催化剂的光纤将光引导到反应堆容器中。如果成功，拟议的工作将为促进现代光化学在工业规模上的实施奠定科学基础，并增强学术光反应工程创新的影响。在光纤上固定光催化剂有望提高光的穿透性和催化过程的效率。由于催化剂是固定化的，不会随着反应器进料连续添加，所提出的方法将提高工艺经济性，并将为生产纯小分子和无催化剂杂质的聚合物提供一条途径。在生物医学和电子应用中，消除这些杂质对于合成高纯度化学品非常重要，因为在这些应用中，痕量金属可能会产生毒性或损害器件性能。这些研究计划有可能加速大规模实施现代和温和的光化学，并通过帮助弥合学术界和产业界的分歧而造福社会。教育和外联活动还将受益于将发展的学术界与工业界的密切联系，通过实地考察和与工业界领导人进行小组讨论，将本科生和研究生与潜在雇主联系起来。此外，该计划将开发和分发廉价的聚合物科学实验室套件，通过改善获得高质量STEM教育体验的机会，使服务不足的初中生和高中生受益。该职业项目将提供将现代光化学的学术进步转化为大规模工业应用所需的基础工程知识。本研究计划的目标是确定有机光氧化还原催化剂的关键化学结构-性质关系，使其能够在不影响催化活性的情况下表面接枝到固定化底物上。通过研究一系列控制光纤消失场的方法，光纤表面系留催化剂将在间歇式和连续流反应器系统中作为多相光催化剂进行测试。催化剂的表面密度将通过表面单层接枝和瓶刷聚合物系绳的使用相结合来控制。一旦确定了最佳的光纤单元间距和分布，工艺吞吐量和可扩展性将不再受光吸收的限制，而完全受反应器大小的限制。通过将光引入反应器，将绕过Beer-Lambert吸收限制，以提供高度可扩展的连续吞吐量方法。由于光催化剂被固定在反应器内(不是连续添加)，它可以回收用于多个反应；此外，最终的化学产品将没有催化剂杂质，这是许多制药和电子化工产品所必需的条件。从教育和推广的角度来看，该计划将通过在大学实体、农村学校和行业合作伙伴之间形成联盟，广泛影响所有年龄和背景的学生。首席调查员将通过实地考察和与行业领导者的小组讨论，增加本科生和研究生与潜在雇主之间的联系。此外，该计划将试点并向中学生分发廉价的聚合物科学实验室套件，通过改善他们获得优质STEM教育的机会，使服务不足的初中生和高中生受益。最后，有针对性的社区外展活动将促进社会经济困难学生的大学入学，同时向非技术观众传播科学原则和可持续发展和塑料垃圾回收的重要性。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Because light can be collected freely or produced efficiently, driving chemical transformations with light instead of heat can have significant advantages over traditional chemical production methods. However, challenges remain in bringing these mostly academic findings to the scale necessary for industrial adoption, limiting the benefits to society that would result from safer and milder chemical processing conditions. An important factor in restricting the scalability of photochemical processes is that while high light absorptivity of the feedstocks is desirable for reaction efficiency, it also limits light penetration depth into the reaction medium. Commonly used photocatalysts can also be prohibitively expensive, and residual catalyst impurities in the final products often leads to discoloration or degradation. To address these limitations, this CAREER project will study the use of photocatalyst-coated optical fibers to guide light into the reactor vessels. If successful, the proposed work will lay the scientific foundations to facilitate the implementation of modern photochemistry on an industrial scale and enhance the impact of academic photo-reaction engineering innovations. Immobilizing photocatalysts on optical fibers is anticipated to improve light-penetration and efficiency of the catalytic process. Because the catalysts are immobilized and will not be added continuously with the reactor feed, the proposed approach will improve the process economics and will provide a path to manufacturing both pristine small molecules and polymers free of catalyst impurities. Eliminating such impurities is of importance for synthesis of high purity chemicals in biomedical and electronic applications where trace metals can introduce toxicity or be detrimental to device performance. The research plans have the potential to accelerate the implementation of modern and mild photochemistries on large scales and benefit society by helping to bridge the academia-industry divide. Education and outreach activities will also benefit from the close academia-industry ties to be developed, connecting undergraduate and graduate students and potential employers through field trips and panel discussions with industry leadership. Further, this program will develop and distribute inexpensive polymer science laboratory kits that will benefit underserved middle and high school students by improving access to a quality STEM education experience.This CAREER project will provide the fundamental engineering knowledge needed to translate academic advances in modern photochemistry to large-scale industrial applications. The objectives of this research program are to identify critical chemical structure-property relationships for organic photoredox catalysts that will enable surface-grafting to immobilizing substrates without affecting catalytic activity. By investigating a range of approaches to control the optical fiber evanescent field, optical fiber surface-tethered catalysts will subsequently be tested as heterogeneous photocatalysts in both batch and continuous-flow reactor systems. Catalyst surface density will be controlled through a combination of surface monolayer grafting and the use of bottlebrush polymer tethers. Once an optimal fiber unit spacing and distribution is identified, process throughput and scalability will no longer limited by light absorption, but exclusively by the size of the reactor. By bringing light into the reactor, Beer-Lambert absorption limitations will be circumvented to provide a highly scalable continuous throughput methodology. Because the photocatalyst is immobilized within the reactor (and not continuously added), it can be recycled for multiple reactions; furthermore, the final chemical product will be free of catalyst impurities, a condition necessary in many pharmaceutical and electronics chemical products. From an educational and outreach perspective, this program will broadly impact students of all ages and backgrounds by forming a coalition between university entities, rural schools, and industrial partners. The principal investigator will increase interfaces between undergraduate and graduate students and potential employers through field trips and panel discussions with industry leadership. Further, this program will pilot and distribute inexpensive at-cost polymer science laboratory kits to secondary students to benefit underserved middle and high school students by improving their access to quality STEM education. Finally, targeted community outreach events will promote university enrollment of socioeconomically challenged students while communicating scientific principles and the importance of sustainability and plastic waste recycling to non-technical audiences.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.