Anionic polymerisation propylene oxide

Figure 20 Reaction scheme for the anionic polymerisation of propylene oxide to form PPG (R is the part of alcohol initiator, M the metal from the catalyst and P the propylene oxide).

One of the older methods to obtain macromers is to add very small quantities of a monomer having a double bond and a polymerisable epoxy group in the same structure to propylene oxide, during the anionic polymerisation. A typical example of such a kind of monomer is allyl glycidyl ether. This monomer copolymerises anionically with PO, giving polyethers with small quantities of lateral double bonds (reaction 6.10). 

Figure 1,11. 125.5 MHz spectra of the backbone region of anionically polymerised poly-(propylene oxide), (a) The normal spectrum the intense signals from interior CH and CHj carbons are indicated the minor peaks are from end-groups (b) the CH subspectrum the labels H-T and H-H indicate CH signals from head-to-tail and head-to-head addition, respectively.

Figure 1.15 (a) The normal head-to-tail addition propagation mode in the anionically catalysed polymerisation of propylene oxide (b) the chain transfer reaction generating an allyl alkoxide. 

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