CAREER: Transport Phenomena and the Uptake of Foreign Species during Crystal Growth

工业结晶是一种广泛的过程，在大宗和精细化学品、食品、药品和大量材料的制造中起着关键作用。结晶过程通常发生在复杂的混合物中，这些混合物中含有正在结晶的所需产品，以及几种其他化学品（例如添加剂或制造过程中的副产品）。在这种情况下，控制这些杂质在结晶材料中的掺入程度对于控制其最终特性（在材料设计中）和减轻潜在的不利健康影响（对于药品）至关重要。该职业奖由美国国家科学基金会材料研究部固态与材料化学项目资助，研究这些外来物质如何与结晶产物相互作用，特别关注它们接近晶体表面时的行为。该项目包括几项研究，旨在调查外来物种对晶体特定表面的吸引力，对生长晶体周围液体的结构进行成像，并研究通过修改周围液体的结构可以实现的结合控制程度。这项研究与教育和推广计划相结合，包括为数百名中学生和高中生举办巧克力结晶研讨会，并为数十名本科生和一名研究生提供工业指导的研究机会。除了在高需求领域对这些学生进行培训之外，研究结果将为开发新的晶体材料奠定基础，这些材料使用掺杂剂来微调其连续体的特性，并有效地拒绝来自制药和食品产品的潜在有毒杂质。技术概述：该职业奖由美国国家科学基金会材料研究部固态和材料化学项目资助，为有机分子晶体生长过程中的异物掺入（杂质或掺杂剂）的研究带来了一种新方法，特别关注中尺度动力学在固溶体形成中的作用。尽管历史上广泛使用无机固溶体来控制材料性能（例如，在金属合金中），而且非化学计量晶格结合是药物中保留潜在有毒工艺杂质的主要机制之一，但学术文献很少研究有机固溶体。由于客体在主体晶格中的非化学计量结合，这些系统提供了在连续体中调谐晶体特性的潜力。该项目将输移理论与激光干涉测量相结合，以确定是什么导致了各向异性客体掺入晶体中面选择性的丧失，对浓溶液晶体生长过程中的客体扩散边界层进行成像和研究，并解释分子固溶体形成过程中热力学平衡的动力学偏差。这些目标与教育和推广计划相结合，将不同层次的学生与晶体工程的相关主题联系起来，同时为他们提供来自工业合作者的直接指导。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 Summary:Industrial crystallization is a widespread process that plays a critical role in the manufacture of bulk and fine chemicals, food products, pharmaceuticals, and a very large number of materials. Crystallization processes often occur from complex mixtures that contain the desired product that is being crystallized, together with several other chemicals (e.g. additives, or by-products from manufacturing). In this context, controlling the extent to which these impurities incorporate in the crystalline material is critical to control its final properties (in materials design) and to mitigate potential adverse health effects (for pharmaceutical products). This CAREER award, funded by the Solid State and Materials Chemistry program in NSF’s Division of Materials Research, investigates how these foreign species interact with the crystallizing product, with particular focus on their behavior as they approach the crystal surface. The project involves several studies set to investigate the attraction of foreign species to specific faces of the crystal, imaging the structure of the liquid that surrounds the growing crystal, and studying the degree of incorporation control that can be achieved by modifying the structure of that surrounding liquid. This research is integrated with an education and outreach plan, involving chocolate crystallization workshops for hundreds of middle and high school students, and research opportunities with industrial mentorship for dozens of undergraduate students and a graduate student. Beyond the training of those students in a field that is in high demand, results from the research will set the grounds for the development of new crystalline materials that use dopants to fine-tune their properties in continuum, and for the effective rejection of potentially toxic impurities from pharmaceutical and food products. Technical Summary:This CAREER award, funded by the Solid State and Materials Chemistry program in NSF’s Division of Materials Research, brings a new approach to the study of guest incorporation (impurities or dopants) during the growth of organic molecular crystals, with specific focus on the role of mesoscale kinetics on the formation of solid solutions. Despite the widespread use of inorganic solid solutions to control material properties throughout history (for example, in metal alloys), and the fact that non-stoichiometric lattice incorporation is one of the primary mechanisms by which potentially toxic process impurities are retained in pharmaceuticals, organic solid solutions are rarely studied in the academic literature. These systems offer potential for tuning crystal properties in continuum, owing to the non-stoichiometric incorporation of the guest in a host’s crystal lattice. This project combines transport theory with laser interferometry to determine what drives the loss of face selectivity in crystals with anisotropic guest incorporation, to image and study the guest’s diffusion boundary layer during crystal growth from concentrated solutions, and to explain kinetic deviations from thermodynamic equilibrium in the formation of molecular solid solutions. These goals are integrated with an education and outreach plan that connects students at very different levels to relevant topics in crystal engineering, while providing them with direct mentorship from industrial collaborators.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.