| Autor: |
Gardiner, James, Martinez ‐ Botella, Ivan, Kohl, Thomas M, Krstina, Julia, Moad, Graeme, Tyrell, Jason H, Coote, Michelle L, Tsanaktsidis, John |
| Předmět: |
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| Zdroj: |
Polymer International; Nov2017, Vol. 66 Issue 11, p1438-1447, 10p |
| Abstrakt: |
Pyrazole-based dithiocarbamates are versatile reversible addition fragmentation chain transfer (RAFT) agents that provide molar mass and dispersity (Ð) control over the radical polymerization of both more and less activated monomers (MAMs and LAMs). In this paper we report on theoretical and experimental findings demonstrating that their activity as RAFT agents can be significantly enhanced by introducing electron-withdrawing substituents to the pyrazole ring. This enhancement is most noticeable inmethyl methacrylate polymerizationwhereproductmolar masses aremore accurately predictedby theRAFTagent concentration, and significantly lower Ð values, with respect to those seen with the parent RAFT agent under similar conditions, are observed. Thus, use of 4-chloro-3,5-dimethyl-1H-pyrazole-1-carbodithioate provides a poly(methyl methacrylate) with the anticipated molar mass and Ð as low as 1.3 at high monomer conversion. Good control is retained for monosubstituted MAMs, styrene, methyl acrylate and N,N-dimethylacrylamide. Lowdispersities and lessmolar mass control are also achieved for homoand copolymerizations with the LAM vinyl acetate, albeit with some retardation. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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