High Molecular Weight Polyalkylene Oxide Polyols by Cationic Polymerisation

2 High Molecular Weight Polyalkylene Oxide Polyols by Cationic Polymerisation 

in Table 7.2 the polymerisation rate constants of PO and EO in anionic and in cationic catalysis are compared. 

PO is approximately 7500-8000 times more reactive in cationic catalysis than in anionic catalysis, at 30 °C and around 20-25 times more reactive in cationic catalysis, at 30 °C, than PO anionic polymerisation at 120 °C. It was observed that in cationic polymerisation, EO is around 50 times less reactive than PO, at 30 °C. However, in anionic catalysis there is a reversed order EO is around 2-3 times more reactive than PO. 

This very high PO polymerisation rate in cationic catalysis, at lower temperatures, is extremely attractive from the technological point of view. 

Unfortunately, the cationic polymerisation of alkylene oxides leads to unpleasant side reactions formation, together with the required polymer, of cyclic oligomers, of dioxane type and crown ether type (reaction 7.17) [3, 9, 35, 36, 45-53, 55]. 

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