Electron spin resonance for identification of free radicals in controlled radical polymerization

长期以来，电子自旋共振(ESR)一直被用来识别未配对的电子物种，如自由基，这些物种在进行塑料工业中常用的自由基聚合时是必不可少的。电子自旋共振被用来跟踪自由基物种的浓度，从而可以确定聚合动力学，这对工业放大和开发新的塑料产品和工艺至关重要。电子自旋共振在识别作为最先进的可控自由基聚合(CRP)过程的基础的中间物种方面尤其重要，这些过程包括可逆加成裂解转移(RAFT)、氮氧化物介导的聚合(NMP)和原子转移自由基聚合(ATRP)。在过去的十年里，这种CRP工艺使聚合物科学发生了革命性的变化，并允许精确控制聚合物的微观结构，可与更严格的离子聚合工艺相媲美，同时保留了传统自由基聚合的许多有益特征。在所有的CRP过程中，自由基浓度由可逆链转移或链终止过程控制，这对保持微观结构控制至关重要。这项建议要求台式ESR研究CRP过程中的中间自由基物种，以便更好地了解控制这种聚合反应的动力学。由ESR动力学研究实现的研究将用于改善对此类聚合的控制，并允许更有效地定制和研究将影响塑料工业各个部门的新聚合物材料的性能。

Electron spin resonance (ESR) has long been used to identify unpaired electron species such as free radicals which are essential in carrying out free radical polymerization commonly used in the plastics industry. ESR has been used to track the concentrations of radical species and thus allow determination of polymerization kinetics that is vital for industrial scale-up and the development of new plastics products and processes. ESR is especially relevant in identifying mediating species that are the foundation for state-of-the-art controlled radical polymerization (CRP) processes such as reversible addition fragmentation transfer (RAFT), nitroxide-mediated polymerization (NMP) and atom transfer radical polymerization (ATRP). Such CRP processes have revolutionized polymer science over the past decade and allow for precise control of polymer microstructure rivaling that of more rigorous ionic polymerization processes while retaining many of the beneficial characteristics of conventional radical polymerization. In all of the CRP processes, the radical concentration is controlled by a reversible chain transfer or chain termination process that is vital for retaining microstructural control. This proposal requests a bench-top ESR to study intermediate radical species during CRP in order to better understand the kinetics governing such polymerizations. The research enabled by the ESR kinetic studies will then be used to improve control of such polymerizations and allow for more effective tailoring and study of properties of new polymeric materials that will impact various sectors of the plastics industry.