CAREER: Characterization of Hybrid Resin Systems Based on Epoxy and Acrylate Functionalities

职业：基于环氧和丙烯酸酯官能团的混合树脂体系的表征

• 批准号: 0133133
• 负责人: Julie Jessop
• 金额: $ 37.5万
• 依托单位: University of Iowa
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0133133&HistoricalAwards=false
• 关键词: CAREER; Characterization; Hybrid; Resin; Systems

Photopolymerization has experienced tremendous growth within the film, coating and ink industries and is leading to new applications in the biomedical, communications, automotive, and aerospace fields as well. The advantages of using light to initiate polymerization rather than heatinclude significant savings in energy costs and processing space and time, solvent-free systems, and increased control over the production of initiating species. Of the possible propagation mechanisms, those that are driven by free radical active centers are the most prevalent; however, these polymerizations are plagued by oxygen inhibition. This has increased interest in using cationic photpolymerization schemes, although these suffer from inhibition by moisture and slower cure rates. In order to address the limitations of these polymerization mechanisms, hybridresin systems have been designed within the past few years to cure using a combination of cationic and free-radical mechanisms under ultraviolet light. These 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 ofthese systems; thus, there is a definite 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 isto characterize the fundamental kinetics of these hybrid resin systems and to correlate the chemical distribution of the species with the resulting physical properties. This goal will be accomplished by:1. Investigating the photopolymerization kinetics of the hybrid resin systems.2. Determining the microscopic composition of the hybrid polymers.3. Evaluating the mechanical properties of the hybrid polymers.The conversion and rate data for these hybrid systems will be obtained using in-situ Raman experiments and corroborated with photo-differential scanning calorimetry experiments. Raman spectroscopy provides a highly sensitive means of following both cationic and free-radical reactions in real time by monitoring the depletion of the epoxide rings and the acrylate double bonds as they are consumed during the polymerization. The physical nature and properties of the resulting polymers will be investigated with Raman microscopy and dynamicmechanical analysis. Results from this research will address important issues on the interactions between the two polymerization systems and will provide guidance that will aid in the design of these reaction systems for established radiation cure industries, as well as provide opportunities for growth in new areas.This research program will also have a direct impact on the educational experience of students at various levels, including those in junior and senior high school. The Engineering Awareness for Students and Teachers program will be developed to introduce secondary studentsand teachers from an urban school district to engineering concepts and college preparation strategies through a summer program and classroom activities. Economically disadvantaged students and female and minority students will be recruited in order to increase the opportunitiesof these underrepresented groups in engineering. This two-pronged approach seeks to increase the impact of the program beyond the students who attend the summer program by supporting their teachers, who will return to their classrooms with materials to introduce all their students tothe excitement and challenges of engineering.

光聚合在薄膜、涂料和油墨行业中经历了巨大的增长，并在生物医学、通信、汽车和航空航天领域产生了新的应用。使用光引发聚合而不是加热聚合的优点包括显著节省能源成本以及加工空间和时间、无溶剂系统以及加强对引发物种生产的控制。在可能的繁殖机制中，那些由自由基活性中心驱动的机制是最普遍的；然而，这些聚合受到氧抑制的困扰。这增加了人们对使用阳离子光聚合方案的兴趣，尽管这些方案受到湿气的抑制和较慢的固化速度。为了解决这些聚合机理的局限性，在过去的几年里，人们设计了杂化树脂体系，在紫外光下结合使用阳离子和自由基固化机理。这些体系对氧气和湿气的敏感性较低，并具有提高固化速度和改善成膜性能等优点。到目前为止，大多数研究都集中在这些体系的开发上，因此，有必要进行深入的研究，以创建基本的知识基础，使这些体系的影响和用途得到优化。本研究将研究基于同时包含环氧化物部分和丙烯酸酯部分的配方的杂化树脂体系，环氧化物部分经历阳离子开环光聚合，丙烯酸酯部分经历自由基光聚合。这项研究的目标是表征这些杂化树脂体系的基本动力学，并将物种的化学分布与所产生的物理性质相关联。这一目标将通过：1.研究杂化树脂体系的光聚合动力学来实现。测定杂化聚合物的微观组成。评价杂化聚合物的力学性能。这些杂化体系的转化率和速率数据将通过原位拉曼实验获得，并通过光差示扫描量热实验得到证实。拉曼光谱提供了一种高度灵敏的手段，通过监测聚合过程中消耗的环氧环和丙烯酸酯双键的消耗，实时跟踪阳离子和自由基反应。我们将用拉曼显微镜和动态力学分析来研究所得聚合物的物理性质和性质。这项研究的结果将解决两种聚合系统之间相互作用的重要问题，并将为现有的辐射固化行业设计这些反应系统提供指导，并为新领域的发展提供机会。该研究计划还将对包括初中和高中在内的各级学生的教育经验产生直接影响。将制定学生和教师工程意识计划，通过暑期计划和课堂活动向城市学区的中学生和教师介绍工程概念和大学准备战略。将招收经济困难学生、女性学生和少数族裔学生，以增加这些代表不足的群体在工程学方面的机会。这种双管齐下的方法试图通过支持他们的老师来增加该项目的影响，超越参加暑期项目的学生，他们会带着材料回到教室，向所有的学生介绍工程学的兴奋和挑战。