Structure of poly(propylene oxide) obtained in the presence of K−, K+(15-crown-5)2

Potassium isopropoxide and potassium tetraethylene glycoxide vinyl ether as well as small amounts of dipotassium tri- and tetraethylene glycoxides are formed in the initiation step of propylene oxide polymerization by K−, K+(15-crown-5)2. Chain transfer reactions occur during the polymerization. Therefore, macromolecules with various starting groups, i.e. with the isopropyl, vinyl, allyl, and propenyl ones, are obtained in the process. The kind of end groups generally depends on the quenching agent used for termination. However, the macromolecules terminated in the chain transfer reactions possess exclusively the hydroxyl end group. The functionality of protonated polymers is equal to about 1.2 as a result of propagation occurring on dipotassium glycoxides.