Department of Chemistry & Chemical Biology, Harvard University , 12 Oxford Street, Cambridge, Massachusetts 02138, United States.
Wyss Institute for Biologically Inspired Engineering, Harvard University , 60 Oxford Street, Cambridge, Massachusetts 02138, United States.
J Am Chem Soc. 2017 Dec 27;139(51):18688-18697. doi: 10.1021/jacs.7b10901. Epub 2017 Dec 13.
This work describes the development of magnetic levitation (MagLev) to characterize the kinetics of free-radical polymerization of water-insoluble, low-molecular-weight monomers that show a large change in density upon polymerization. Maglev measures density, and certain classes of monomers show a large change in density when monomers covalently join in polymer chains. MagLev characterized both the thermal polymerization of methacrylate-based monomers and the photopolymerization of methyl methacrylate and made it possible to determine the orders of reaction and the Arrhenius activation energy of polymerization. MagLev also made it possible to monitor polymerization in the presence of solids (aramid fibers, and carbon fibers, and glass fibers). MagLev offers a new analytical technique to materials and polymer scientists that complements other methods (even those based on density, such as dilatometry), and will be useful in investigating polymerizations, evaluating inhibition of polymerizations, and studying polymerization in the presence of included solid materials (e.g., for composite materials).
这项工作描述了磁悬浮（MagLev）的发展，用于表征水溶性低分子量单体的自由基聚合动力学，这些单体在聚合时密度会发生很大变化。MagLev 测量密度，某些类别的单体在共价键合形成聚合物链时密度会发生很大变化。MagLev 对基于甲基丙烯酸酯的单体的热聚合以及甲基丙烯酸甲酯的光聚合进行了表征，并能够确定聚合反应的级数和聚合的阿仑尼乌斯活化能。MagLev 还能够监测固体（芳纶纤维、碳纤维和玻璃纤维）存在下的聚合反应。MagLev 为材料和聚合物科学家提供了一种新的分析技术，补充了其他方法（即使是基于密度的方法，如膨胀计），将有助于研究聚合反应、评估聚合反应的抑制以及研究包含固体材料存在时的聚合反应（例如，用于复合材料）。
