The cationic polymerization of two new divinyl ethers, 1-(2-vinyloxyethoxy)-2[(2-vinyloxyethoxy)carbonyl]benzene (2) and 1,2-bis[(2-vinyloxyethoxy)carbonyllbenzene (3), as well as 1,2-bis(2-vinyloxyethoxy)benzene (1), with BF3OEt2 in CH2Cl2 at 0 degreesC at low initial monomer concentrations ([M](0) = 0.15 and 0.075 M) gave soluble polymers with relatively high molecular weights and broad molecular weight distributions (MVMs), whereas reactions with the HCI/ZnCl2 initiating system yielded soluble polymers with relatively narrow MWDs (weight-average molecular weight/number-average molecular weight less than or similar to 1.6) under similar reaction conditions. An NMR structural analysis of the HCI/ZnCl2-mediated polymers from the divinyl ethers showed that poly(l) had virtually no unreacted vinyl ether groups throughout the polymerization (monomer conversion = 28-98%), whereas poly(2) and poly(3) possessed some amount of unreacted vinyl ether groups in the initial stage of the polymerization; the content of the vinyl groups of poly(2) was 18 mol % at a 15% monomer conversion, and the content of the vinyl groups of poly(3) was 31 mol % at an 18% monomer conversion. Therefore, divinyl ether 1 underwent cyclopolymerization exclusively to give almost completely cyclized polymers [degree of cyclization (DC) similar to 100%], whereas divinyl ethers 2 and 3 exhibited a lower cyclopolymerization tendency [DC for poly(2) = 82%; DC for poly(3) = 69%]. The differences in the cyclopolymerization tendencies among the divinyl ethers can be explained by the differences in the solvation powers of the neighboring functional groups adjacent to the vinyl ether moiety with the active center: the ether oxygen of the ether neighboring group solvates intramolecularly with the active center to accelerate the intramolecular propagation, but such an interaction is less effective with the more electron-deficient oxygen attached to the carbonyl group of the ester neighboring group.