Different cationic catalyst systems used in the homopolymerization and copolymerization of ECH were reviewed. The removal methods of the cyclic oligomers from the products were outlined. Some novel synthesis methods were introduced, such as the synthesis method of ECH-styrene block copolymer by combination of the cation and free radical polymerization, the method to produce isotactic PECH which can be used to prepare thermoplastic GAP.
