In situ CP MAS NMR spectroscopy under continuous-flow conditions to monitor real time dynamics during propene polymerization over a supported Ziegler catalyst

In situ propene polymerization was observed using CP MAS (cross polarization with magic angle spinning) ¹³C NMR spectroscopy under the conditions of continuously flowing propene through a supported Ziegler catalyst treated with triethylaluminium. The signals at 44, 26, and 22 ppm attributed to the CH₂, CH, and CH₃ groups of polypropene, respectively, were found to appear upon exposure to the propene flow (0.1 L/min). An increase in intensities of these lines was observed for 30 min, then they remained approximately constant. The cross-polarization parameters of nascent polypropene, measured using standard techniques, were close to those of typical crystalline polypropene. The technique has a great potential as an effective tool for the investigation of the polypropene formation on the Ziegler catalyst.