Living/controlled cationic cyclopolymerization of divinyl ether with a cyclic acetal moiety: Synthesis of poly(vinyl ether)s with high glass transition temperature based on incorporation of cyclized main chain and cyclic side chains
2010
Hashimoto, Tamotsu | Takagi, Hiromi | Hasegawa, Yuko | Matsui, Haruki | Urushisaki, Michio | Sakaguchi, Toshikazu
Cationic cyclopolymerization of 2-methyl-5,5-bis(vinyloxymethyl)-1,3-dioxane (1), a divinyl ether with a cyclic acetal group, was investigated with the HCl/ZnCl₂ initiating system in toluene and methylene chloride at -30 °C. The reaction proceeded quantitatively to give gel-free, soluble polymers in organic solvents. The number-average molecular weight (Mn) of the polymers increased in direct proportion to monomer conversion, and further increased on addition of a fresh monomer feed to the almost completely polymerized reaction mixture, indicating that the polymerization proceeded in living/controlled manner. The contents of the unreacted vinyl groups in the produced soluble polymers were less than ~3 mol %, and therefore, the degree of cyclization was determined to be ~97%. In contrast, the pendant cyclic acetal groups remained intact in the polymers under the present cationic polymerization conditions. These facts show that cyclopolymerization of 1 almost exclusively occurred and the poly(vinyl ether)s with the cyclized repeating units and cyclic pendant acetal rings were obtained. Glass transition temperature (Tg) and thermal decomposition temperature (Td) of poly(1) (Mn = 7870, Mw/Mn = 1.57) were found to be 166 and 338 °C, respectively, indicating that poly(1) had high Tg and high thermal stability.
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