Hoogenboom, Richard, et al. Journal of Polymer Science Part A: Polymer Chemistry, 2005, 43(7), 1487-1497.
This article described the cationic ring-opening polymerization of 2-ethyl-2-oxazoline in N,N-dimethylacetamide (DMAc) with automated parallel control of monomer concentration. It was studied by comprehensive 1H-NMR spectroscopy in which the polymerisation reaction was monitored with the NMR spectrometer using N,N-dimethylacetamide-d9 (DMAc-d9).
Monitoring Polymerizations with NMR
Benzyl bromide (at 8 M: 22.8 mg; 1 M: 2.8 mg), 2-ethyl-2-oxazoline (at 8 M: 792 mg; 1 M: 99.1 mg), and DMAc-d9 (at 8 M: 200 µL; 1 M: 900 µL) were measured in dried 5 mL vials. From these polymerization mixtures, 0.5 mL was transferred to an NMR tube. The polymerization commenced once the tube was inserted into an NMR probe preheated to 100 °C. At designated intervals, 1H-NMR spectra were captured to observe the polymerization progress. Monomer conversion was calculated based on the integrals of both the monomer and polymer signals, while the initiation process was tracked by integrating the signals from benzyl bromide. The quantity of cationic species was assessed by comparing the CH2 signals of the oxazolinium species to the aromatic initiator signals.
