Herein, we clarified the ring-expansion cationic polymerization with a cyclic hemiacetal ester (HAE)-based initiator was versatile in terms of applicable vinyl ether monomers. Although there was a risk that higher reactive vinyl ethers may incur b-H elimination of the HAE-based cyclic dormant species to irreversibly give linear chains, the polymerizations were controlled to give corresponding cyclic polymers from various alkyl vinyl ethers of different reactivities. Functional vinyl ether monomers were also available, and for instance a vinyl ether monomer carrying an initiator moiety for metal-catalyzed living radical polymerization in the pendant allowed construction of ring-linear graft copolymers through the grafting-from approach. Furthermore, ring-based gel was prepared via the addition of divinyl ether at the end of the ring-expansion polymerization, where multi HAE bonds cyclic polymers or fused rings were crosslinked with each other. (C) 2017 Wiley Periodicals, Inc.