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Propagation Kinetics of Binary Acrylate–Methacrylate Free-Radical Bulk Copolymerizations

2007; Wiley; Volume: 208; Issue: 6 Linguagem: Inglês

10.1002/macp.200600547

1521-3935

Michael Buback, Elena K. Müller,

Radical Photochemical Reactions

Abstract Rate coefficients of propagation, k p,copo , for MA–MMA, MA–DMA, DA–MMA, and DA–DMA bulk copolymerizations have been determined via PLP–SEC. The k p,copo values are analyzed in terms of the terminal and penultimate unit effect models. Alkyl acrylate and alkyl methacrylate reactivity ratios, as obtained from copolymer composition, are not significantly dependent on the size of the alkyl ester moiety, whereas k p,copo clearly depends on the size of the alkyl group. For MA–DMA, an almost perfect simultaneous fit of copolymer composition and k p,copo is obtained via the terminal model. For DA–MMA, even the penultimate unit effect model affords no adequate simultaneous fit. The observed effects are assigned to hindrance of internal rotational motion in the transition state due to intermolecular and intramolecular mobility terms. magnified image