To clarify the effects of the central spacer chain structure of divinyl ethers on their cationic cyclopolymerization tendencies, 1,4-bis [(2-vinyloxy)ethoxy]benzene (1), 1,4-bis[(2-vinyloxy)ethoxy]butane (2), 1,6-bis[(2-vinyloxy)ethoxy]hexane (3), 1,8bis [(2-vinyloxy)ethoxy]octane (4), and 1,4-bis[(4-vinyloxy)butoxy]butane (5) were polymerized with the hydrogen chloride/zinc chloride (HCl/ZnCl2) initiating system in methylene chloride (CH2Cl2) at 0degreesC at low initial monomer concentration ([M](0) = 0.15 M). The polymerizations of divinyl ethers 2 and 3 gave soluble polymers quantitatively. In contrast, the polymerizations of divinyl ethers 1, 4, and 5 underwent gel formation at high monomer conversion. The content of the unreacted vinyl groups of the obtained soluble polymers was measured by H-1 NMR spectroscopy. Judging from the relatively low vinyl contents of the polymers produced even in the early stage of the polymerization (monomer conversion < similar to20%), the cyclopolymerization occurred to some extent for 2, 3, and 4. On the contrary, the polymers produced from 1 and 5 exhibited the relatively high vinyl content, indicating that the cyclopolymerization tendencies of 1 and 5 were lower than those of 2, 3, and 4. These results are discussed in terms of the structural variety of the spacer chains: (1) the presence of benzene ring (1 vs 2), (2) their length (2 vs 3 and 4), and (3) the position of ether oxygen (4 vs 5).