Application of FT-NIR Spectroscopy for Monitoring the Kinetics of Living Polymerizations
Fourier-transform near infrared (FT-NIR) spectroscopy in combination with a fiber optic probe was successfully used to monitor the living cationic polymerization of isobutylene (IB) and the living anionic polymerization of ethylene oxide (EO) and butadiene (B). After the development of online monitoring techniques for the living anionic polymerizations of styrene (S) and isoprene in the near infrared range (NIR), methods were developed that allow to follow the polymerization of IB and S in the mid-infrared (MIR) range. It was believed that NIR could not be used for IB due to overlapping signals. In this paper we show that even in the NIR specific signals of the monomer can be used for monitoring conversion without using deconvolution methods in IB as well as EO and B polymerizations. In the case of EO a temperature dependent induction period was found with sec-butyllithium and the phosphazene base t-BuP4 as initiating system.
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