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

固化油墨、薄膜和涂料排放的挥发性有机成分(VOC)是造成大气污染的主要原因。传统上，挥发性有机溶剂被用来赋予油墨和涂料配方理想的粘度和固化速率特性。油墨或涂料配方必须具有足够的流动性，以便于涂布(通常通过一系列转印辊快速移动到基材上)，但必须迅速固化成坚硬的薄膜。从历史上看，这些加工要求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。当这些挥发性有机溶剂进入大气时，会造成烟雾和空气污染。需要开发不会向大气中排放VOCs的高性能油墨和涂料。二环氧化合物和双乙烯基醚的阳离子光聚合具有开发高性能油墨和涂料的潜力，这些油墨和涂料在固化过程中不释放VOCs。然而，由于合适的单体和引发剂最近才被开发出来，这些反应的特征和所得到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性的实验和理论研究。使用原位时间分辨荧光和拉曼实验将获得反应温度和反应程度的详细轮廓，并将彻底表征所得到的高度交联性聚合物薄膜的热、机械和物理性质。核磁共振自旋扩散实验将被用来研究聚合物薄膜的均匀性和形貌。理论工作的目标是开发计算机模拟光聚合反应，以现实的方式解释分子的迁移率。这些模拟应该有助于深入了解高度交联型网络结构的发展。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.