Real‐time monitoring by proton relaxometry of radical polymerization reactions of acrylamide in aqueous solution |
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| Authors: | Elton Jorge da Rocha Rodrigues Roberto Pinto Cucinelli Neto Pedro José Oliveira Sebastião Maria Inês Bruno Tavares |
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| Affiliation: | 1. Instituto de Macromoléculas Professora Eloisa Mano da Unidade Federal do Rio de Janeiro, Centro de Tecnologia, Ilha do Fund?o, Rio de Janeiro, Brazil;2. Center of Physics and Engineering of Advanced Materials, Instituto Superior Técnico, Universidade de Lisboa, Portugal |
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| Abstract: | The potential of time‐domain nuclear magnetic resonance (TD‐NMR) for the real‐time monitoring of solution radical polymerizations is demonstrated. A model system composed of a redox‐pair initiator system, acrylamide as monomer and water as solvent was investigated. A second‐generation continuous wave free precession technique was employed to measure the longitudinal relaxation time constant (T1) of the samples throughout the polymerization reactions. This parameter was shown to be sensitive to the reactant feed free‐radical enhancement of the water molecule relaxation time, making it a good probe to monitor monomer conversion in real time in an automated, non‐destructive fashion. It was found that the T1 value was better than the transverse relaxation time constant (T2) for describing the evolution of the polymerization reactions, due to its greater sensitivity to paramagnetic effects. The TD‐NMR signal variation observed was linked to the formation, propagation and termination steps of the radical polymerization kinetics scheme. These first results may contribute to the application of real‐time monitoring of radical polymerization reactions employing low‐cost and robust TD‐NMR spectrometers. © 2018 Society of Chemical Industry |
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| Keywords: | time‐domain NMR CP‐CWFP CMPG reaction monitoring radical polymerization |
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