Abstract
The kinetics of the cationic ring‐opening polymerization of propylene sulfide initiated with different initiators has been investigated and the results were compared with those obtained with triethyloxonium tetrafluoroborate as described in a previous paper. With triethyloxonium hexafluorophosphate, the polymerization showed the same characteristics, that is: an initial very fast non‐stationary stage A is followed by a much slower stage B which leads to quantitative conversion. With triethyloxonium hexachloroantimonate, the B‐stage stopped at limited conversions which was attributed to a sulfonium ion‐destroying termination reaction between the growing species and the SbCl anion to give an alkylchloride and SbCl~5~. Perchloric acid gives a polymerization which is analogous to the oxonium tetrafluoroborate initiated polymerizations which indicates that perchloric acid also gives a rapid and quantitative initiation reaction. Methyl fluorosulfonate on the contrary is a slow initiator. In the polymerization with boron trifluoride etherate, water acts as a co‐initiator and the maximum activity is reached at a ratio H~2~O/BF~3~OEt~2~ equal to 0,5. All polymerizations, with the exception of that initiated with triethyloxonium hexachloroantimonate, are of the dormant type and the polymers slowly degrade to form a mixture of low molecular weight polymer and cyclic oligomers, mainly tetramer.