Critically evaluated rate coefficients for free-radical polymerization Part 6: propagation rate coefficient of methacrylic acid in aqueous solution

Chemistry International, Nov-Dec, 2007 by Sabine Beuermann, Michael Buback, Pascal Hesse, Frank-Dieter Kuchta, Igor Lacik, Alex M. van Herk

Pure and Applied Chemistry

Vol. 79, No 8, pp. 1463-1469, 2007

doi:10.1351/pac200779081463

Critically evaluated propagation rate coefficients, [k.sub.p], for free-radical polymerization of methacrylic acid, MAA, in aqueous solution are presented. The underlying [k.sub.p] values are from two independent sources, which both used the IUPAC-recommended technique of pulsed-laser-initiated polymerization (PLP) in conjunction with molar mass distribution (MMD) analysis of the resulting polymer by size-exclusion chromatography (SEC). Different methods of measuring the MMD of the poly(MAA) samples have, however, been used: (i) direct analysis via aqueous-phase SEC and (ii) standard SEC with tetrahydrofuran as the eluent carried out on poly(methyl methacrylate) samples obtained by methylation of the poly(MAA) samples from PLP. Benchmark [k.sub.p] values for aqueous solutions containing 15 mass % MAA are presented for temperatures between 18 and 89[degrees]C. The Arrhenius pre-exponential and activation energy of [k.sub.p] at 15 mass % MAA are 1.54 x [10.sup.6] L [mol.sup.-1] [s.sup.-1] and 15.0 kJ [mol.sup.-1], respectively. Also reported are critically evaluated [k.sub.p] values for 25[degrees]C over the entire MAA concentration range from dilute aqueous solution to bulk polymerization.

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