Epoxy-Acrylate Hybrid Resin Systems: Photopolymerizations Outside the (Controlled Atmosphere) Box

0853411科普知识优点：由自由基活性中心驱动的传播机制受到氧抑制的困扰。阳离子聚合方案遭受水分效应和较慢的固化速率。为了解决这些机制的局限性，混合树脂系统已被设计成使用阳离子和自由基机制的组合进行光聚合。(The使用光而不是热来引发聚合的优点包括显著节省能量成本、加工空间和时间;无溶剂体系;和增加对引发物质的生产的控制。这些混合体系对氧气和水分的敏感性较低，并具有提高固化速度和改善成膜性能等优点。迄今为止，大多数研究都集中在这些系统的开发上;因此，需要进行深入的研究，以建立一个基本的知识基础，使这些系统的影响和效用得到优化。这项研究将调查混合树脂系统的基础上，配方含有环氧部分，它经历阳离子开环光聚合，和丙烯酸酯部分，其经历自由基光聚合。本研究的目标是更好地了解实验变量如何影响这些系统（混合单体和多单体系统）的大气敏感性，这反过来又将促进混合单体或系统在实际配方中的最佳结合。这一目标将通过以下方式实现：-确定在混合单体/系统中改变氧扩散影响区域的最有影响力的因素。表征混合单体/体系中光引发剂体系之间的相互作用及其对动力学和物理性能的影响。阐明水对杂化聚合物的动力学和物理性能的影响。评价通过混合单体/体系的引入对丙烯酸酯和环氧化物配方的改进。将使用拉曼和近红外光谱以及拉曼共聚焦显微镜获得转化率、聚合速率和组成。动态力学分析和表面硬度测试将用于关联聚合物组合物与物理性能。这种动力学和物理信息的比较将有助于这些聚合物的反应设计，并将解决两个光聚合系统之间的相互作用的重要问题。研究结果将为定制树脂配方以满足特定的最终用途应用（尤其是薄膜、涂料和粘合剂）提供深入的见解。这项研究可以通过降低与对抗氧抑制相关的成本，促进更快的反应，降低产品质量对湿度条件的依赖性，提供具有更好表面性能的聚合物，并且能够在环境条件下制备薄膜。这种特性也将为生物医学、电信和航空航天工程领域的新应用提供增长机会。该项目还将对各级学生的教育经历产生直接影响。工程和科学专业的学生将受益于聚合物科学系列课程，该课程将结合这些研究成果。一些本科生和高中教师和/或学生将被邀请参加本研究的部分。“带路项目”爱荷华州将通过暑期培训计划和学年课程向中学生和教师介绍工程概念。

0853411JessopIntellectual Merit: Propagation mechanisms that are driven by free-radical active centers are plagued by oxygen inhibition. Cationic polymerization schemes suffer from moisture effects and slower cure rates. To address the limitations of these mechanisms, hybrid resin systems have been designed to photopolymerize using a combination of cationic and free-radical mechanisms. (The advantages of using light to initiate polymerization rather than heat include significant savings in energy costs, processing space, and time; solvent-free systems; and increased control over the production of initiating species.) These hybrid systems exhibit lower sensitivity to oxygen and moisture and offer advantages such as increased cure speed and improved film-forming properties. To date, most studies have focused on the development of these systems; thus, there is a need for in-depth studies in order to create a fundamental base of knowledge that allows the impact and utility of these systems to be optimized.This research will investigate hybrid resin systems based on formulations that contain both an epoxide moiety, which undergoes cationic ring-opening photopolymerization, and an acrylate moiety, which undergoes free-radical photopolymerization. The goal of this research is to acquire a better understanding of how experimental variables affect the atmospheric sensitivity of these systems (both hybrid monomers and multi-monomer systems), which in turn will facilitate the optimal incorporation of hybrid monomers or systems in practical formulations. This goal will be accomplished by:- Determining the most influential factors in altering the oxygen-diffusion-affected region in hybrid monomers/systems.- Characterizing the interplay between photoinitiator systems in hybrid monomers/systems and their effects on kinetics and physical properties.- Clarifying the effect of water on the kinetics and physical properties of hybrid polymers.- Evaluating improvements made in acrylate and epoxide formulations by the incorporation of hybrid monomers/systems.Conversion, rate of polymerization, and composition will be obtained using Raman and near-infrared spectroscopies and Raman confocal microscopy. Dynamic mechanical analysis and surface hardness testing will be used to correlate polymer composition with physical properties. Comparisons of this kinetic and physical information will aid in reaction design for these polymers and will address important issues on the interactions between the two photopolymerization systems. Results will provide insight for tailoring resin formulations to specific end-use applications, especially in films, coatings, and adhesives.Broader Impacts: This research could impact the photopolymerization industries by decreasing costs associated with combating oxygen inhibition, facilitating faster reactions, decreasing the dependence of product quality upon humidity conditions, providing polymers with better surface properties, and enabling the production of thin films at ambient conditions. This characterization will also provide opportunities for growth of new applications in the fields of biomedicine, telecommunications, and aerospace engineering. The project will also have a direct impact on the educational experience of students at various levels. Students in engineering and science will benefit from a polymer science course series that will incorporate these research results. Several undergraduate students and high-school teachers and/or students will be invited to participate in portions of this research. Project Lead the Way Iowa will introduce secondary students and teachers to engineering concepts through a summer training program and academic-year classes.