Coupled UV鈥揤is/FT鈥揘IR Spectroscopy for Kinetic Analysis of Multiple Reaction Steps in Polymerizations

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• 作者：Alan Aguirre-Soto ; Albert T. Hwang ; David Glugla ; James W. Wydra ; Robert R. McLeod ; Christopher N. Bowman ; Jeffrey W. Stansbury
• 刊名：Macromolecules
• 出版年：2015
• 出版时间：October 13, 2015
• 年：2015
• 卷：48
• 期：19
• 页码：6781-6790
• 全文大小：666K
• ISSN：1520-5835

文摘

We couple UV鈥搗is and FT鈥揘IR spectroscopy for the real-time monitoring of polymerization reactions, allowing the simultaneous tracking of the rates of light absorption and initiator/monomer consumption, from which dynamic and previously difficult-to-measure parameters are calculated: quantum yields of initiator consumption, initiation and polymerization, photosensitivity, and residual content of leachable chromophore. Estimating these parameters from one set of experiments is not possible with any other probing technique. We demonstrate the potential of this technique using the free radical initiating system including camphorquinone as photoreducible chromophore and amines as reductants for the visible-light-triggered bulk polymerization of methacrylate monomers, important for dental and biomaterials. Photoinitiation by camphorquinone/amine pairs in two dimethacrylates serves to show the importance of obtaining quantum yields in the polymerizing medium instead of using inert solvents. Additionally, the often-intricate interactions between initiation reactions and the developing macromolecular architectures can be elucidated. For instance, we present the quantification of fluctuations in quantum yields as a function of polymerization. This robust analytical tool with up to millisecond resolution opens opportunities in gaining mechanistic insights from the myriad of macromolecular syntheses available to date.