Kinetics, Structure, and Properties of Crosslinked Polymer Films Formed by Cationic Photopolymerization

油墨、薄膜和涂料固化过程中挥发性有机成分（VOCs）的排放是大气污染的主要原因。挥发性有机溶剂传统上被用来赋予理想的粘度和固化速率性能的油墨和涂料配方。油墨或涂料配方必须具有足够的流动性，以便易于涂抹（通常通过一系列转移辊涂在快速移动的承印物上），但必须迅速固化成硬膜。从历史上看，通过在油墨和涂料配方中使用快速蒸发的有机溶剂来满足这些加工要求。当这些挥发性有机溶剂进入大气时，就会形成烟雾和空气污染。有必要开发不向大气排放挥发性有机化合物的高性能油墨和涂料。二氧化物和双乙烯醚的阳离子光聚合表现出在固化过程中不释放挥发性有机化合物的高性能油墨和涂料的发展潜力。然而，由于合适的单体和引发剂直到最近才被开发出来，这些反应的特性和所产生的聚合物膜的结构还不是很清楚。本研究项目将为紫外光引发的阳离子光聚合提供基础的实验和理论研究。反应温度和反应程度的详细概况将通过原位时间分辨荧光和拉曼实验获得，并且所得到的高交联聚合物薄膜的热、机械和物理性质将被彻底表征。核磁共振自旋扩散实验将用于研究聚合物薄膜的均匀性和形貌。理论努力的目标是发展光聚合反应的计算机模拟，以现实的方式解释分子的迁移性。这些模拟应该提供深入了解高交联网络结构的发展。这项研究将有助于评估这些反应在开发高性能、无溶剂油墨和涂料方面的潜力。

The emission of volatile organic components (VOCs) from curing inks, films and coatings is a leading cause of atmospheric pollution. Volatile organic solvents have traditionally been used to impart desirable viscosity and cure rate properties to ink and coating formulations. An ink or coating formulation must be sufficiently fluid to be easily applied (often onto a rapidly moving substrate through a series of transfer rollers), but must cure rapidly to a hard film. Historically, these processing demands have been met through the use of a rapidly evaporating organic solvent in the ink and coating formulations. When these volatile organic solvents enter the atmosphere, they result in the formation of smog and air pollution. There is a need for the development of high performance inks and coatings that will not emit VOCs to the atmosphere. Cationic photopolymerizations of diepoxides and bisvinyl ethers exhibit potential for the development of high- performance inks and coatings which emit no VOCs during cure. However, because appropriate monomers and initiators have been developed only recently, the characteristics of these reactions and the structure of the resulting polymer films are not well understood. This research project will provide fundamental experimental and theoretical investigations of UV- initiated cationic photopolymerizations. Detailed profiles of the reaction temperature and the extent of reaction will be obtained using in situ time-resolved fluorescence and raman experiments, and the thermal, mechanical, and physical properties of the resulting highly crosslinked polymer films will be thoroughly characterized. Nuclear magnetic resonance spin diffusion experiments will be used to investigate the homogeneity and morphology of the polymer films. The goal of the theoretical effort is to develop computer simulations of the photopolymerization reactions which account for molecular mobility in a realistic manner. These simulations should provide insight into the development of the highly crosslinked network structure. The research will help evaluate the potential of these reactions for the development of high- performance, solvent-free inks and coatings.