Jessen Luis L, Hansen Kameron R, Crull George B, Grover Tanner L, Guymon C Allan
Department of Chemical and Biochemical Engineering, The University of Iowa, Iowa City, Iowa 52242, United States.
Department of Chemistry, The University of Iowa, Iowa City, Iowa 52242, United States.
ACS Macro Lett. 2025 Jun 17;14(6):847-852. doi: 10.1021/acsmacrolett.5c00171. Epub 2025 Jun 4.
The ability to precisely measure photopolymerization kinetics is paramount to controlling curing characteristics and material properties in photocurable systems. Traditional methods used to measure kinetics, such as real-time Fourier-transform infrared spectroscopy (RT-IR), are often limited by broadening mechanisms intrinsic to the system and poor spectral resolution. In this work, we present an NMR spectroscopy technique to monitor bulk photopolymerization reactions wherein the polymer system is separated from the locking solvent via a capillary insert and photoexcited using an LED-coupled fiber optic. This technique allows for the isolated observation of the bulk reaction system while also benefiting from the high spectral resolution and rich chemical information offered by NMR. Relative rate constants (') and ultimate monomer conversion were determined for four systems: neat hexyl acrylate, isobornyl methacrylate, ,-dimethylacrylamide, and hexyl acrylate with cross-linker. By observing kinetic data of simple photopolymer systems, this work demonstrates the utility of NMR photopolymerization as a complementary technique to conventional RT-IR and other methods for the kinetic monitoring of bulk photopolymer materials.
精确测量光聚合动力学的能力对于控制光固化体系中的固化特性和材料性能至关重要。用于测量动力学的传统方法，如实时光傅里叶变换红外光谱（RT-IR），常常受到体系固有展宽机制和较差光谱分辨率的限制。在这项工作中，我们提出了一种核磁共振光谱技术来监测本体光聚合反应，其中聚合物体系通过毛细管插入物与锁定溶剂分离，并使用发光二极管耦合光纤进行光激发。该技术能够对本体反应体系进行单独观测，同时受益于核磁共振提供的高光谱分辨率和丰富化学信息。测定了四个体系的相对速率常数（'）和最终单体转化率，这四个体系分别为：纯丙烯酸己酯、甲基丙烯酸异冰片酯、N，N-二甲基丙烯酰胺以及添加交联剂的丙烯酸己酯。通过观察简单光聚合体系的动力学数据，这项工作证明了核磁共振光聚合作为一种补充技术，可用于常规RT-IR和其他方法对本体光聚合材料进行动力学监测。
