GOALI: Connecting the Dots: Using Radical-formation Control to Achieve Desired EB-initiated Polymer Properties

爱荷华大学和电子束技术公司(ET)建议建立一个联合的学术和产业合作伙伴关系，以研究聚合物的电子束固化基础科学。这项工作可以消除聚合中对自由基引发剂的需求，有助于理解电子束引发步骤的机理，并可能导致更均匀的固化轮廓。与热干燥和固化过程相比，电子束(EB)固化提供了一种更快、更低功率和无溶剂的聚合油墨、薄膜、涂料和粘合剂的方法。该研究项目的目标是通过发展结构-加工性能关系来推进EB固化技术，该关系结合了关于化学结构如何影响自由基的形成和反应的基本知识。这一理解也将使电子束固化技术能够扩展到更广泛的应用，包括用于汽车和航空航天工业的高性能材料以及用于食品和医疗产品工业的低迁移材料。将进行以下研究：(1)辐射产额与单体结构的相关性，(2)具有相同自由基浓度的电子束固化和紫外光固化体系中性能发展的比较，(3)通过单体结构和组成控制交联剂密度，以及(4)通过单体结构和组成最小化迁移。将使用光谱技术测量动力学速率和自由基浓度，以获得单体引发效率。使用凝胶渗透色谱和动态力学分析来测量分子量分布(对于线性聚合物)、交联度(对于聚合物网络)和力学性能，以展示引发机理、单体结构和工艺参数对聚合物物理性能的影响。将使用气相色谱/质谱仪来识别和量化超低迁移系统的可浸出物质及其扩散系数。EB动力学和所得聚合物性能之间高级关系的发展可能会提供对EB固化系统的更高水平的理解，远远超出目前可用的水平。除了在与工业相关的研究领域培训研究生外，还计划在结合项目成果的聚合物演示的基础上，向K-12和STEM本科生开展外联活动。该奖项反映了NSF的法定使命，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，被认为是值得支持的。

A joint academic-industrial partnership between the University of Iowa and ebeam Technologies (eT) is proposed to study fundamental science of electron beam curing of polymers. The work could eliminate the need for free-radical initiators in polymerization, help understand the mechanism of the initiation step by ebeam, and could lead to more uniform curing profiles. Electron-beam (EB) curing offers a faster, lower-power, and solvent-free means of polymerizing inks, films, coatings, and adhesives when compared to thermal drying and curing processes. The goal of this research project is to advance EB-curing technologies by developing structure-processing property relationships that incorporate the fundamental knowledge of how chemical structure influences radical formation and reactivity. This understanding will also enable the extension of EB-curing technologies to a wider range of applications, including high-performance materials for the automotive and aerospace industries and low-migration materials for the food and medical product industries.The following research topics will be pursued: (1) correlation of the radiation yield with monomer structure, (2) comparison of property development in EB- and UV-cured systems having equal radical concentration, (3) control of crosslink density through monomer structure and composition, and (4) minimization of migration through monomer structure and composition. Kinetic rates and radical concentrations will be measured using spectroscopic techniques to obtain monomer initiation efficiencies. Molecular weight distributions (for linear polymers), crosslink density (for polymer networks), and mechanical properties will be measured using gel permeation chromatography and dynamic mechanical analysis to demonstrate the impact of initiation mechanism, monomer structures, and process parameters on polymer physical properties. Gas chromatography/mass spectrometry will be used to identify and quantify leachable materials and their diffusion coefficients for ultra-low-migration systems. Development of advanced relationships between EB kinetics and the resulting polymer properties may provide a level of understanding of EB-cured systems significantly beyond what is now available. In addition to training graduate students in an industrially-relevant area of study, outreach activities to K-12 and undergraduate students in STEM are planned based on polymer demonstrations incorporating project results. Special emphasis will be placed on recruiting underrepresented female and minority students to participate in this research project.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.