ABSTRACT The multiphasic semi‐batch ring‐opening polymerization of propylene oxide was investigated with respect to mass‐transfer limitations at the solid–liquid and liquid–catalyst interfaces, and their impact on the polydispersity and viscosity of the resulting polypropylene glycol. To enable this analysis, a method for determining polymerization rate constants was developed based on modelling the time‐dependent propylene oxide concentration during continuous dosage. The method's applicability was validated through activation‐energy determination. The results show that polymerization is primarily governed by mass‐transfer limitations at the liquid–catalyst interface, while gas–liquid transport limitations, though present, have minimal influence on the final polymer properties.
Thiel et al. (Mon,) studied this question.