Accessing the chain length dependence of the termination rate coefficient for disparate length radicals via reversible addition fragmentation chain transfer chemistry: A theoretical study

作者：Lovestead Tara M; Theis Alexander; Davis Thomas P; Stenzel Martina H; Barner Kowollik Christopher^*

来源：Macromolecules, 2006, 39(15): 4975-4982.

DOI：10.1021/ma060646x

On the basis of the recently introduced reversible addition fragmentation chain transfer chain length dependent termination (RAFT-CLD-T) method, a novel approach is presented to access the termination rate coefficient for disparate length radicals, k(t)(s,l). In-depth simulation is employed to validate this approach, which utilizes reversible addition fragmentation chain transfer ( RAFT) chemistry to generate two nearly monodisperse chain length distributions with disparate average lengths, s and l. These disparate length radicals are generated by prepolymerizing a polyRAFT species to a chain length significantly greater than unity and subsequently progressing the polymerization of the polyRAFT species in the presence of a suitable RAFT agent of initial chain length 1. The present study demonstrates that the chain length dependence of the termination rate coefficient for disparate length radicals can be obtained accurately regardless of the extent of the prepolymerization period of the polyRAFT species, the input kinetic parameters, and whether the geometric or the harmonic mean approximation is assumed for the relationship between k(t) and the individual radical chain lengths s and l. Thus, for the first time a facile and accurate method for quantification of k(t)(s,l) is validated theoretically allowing for a complete characterization of free radical termination processes for disparate length radicals.

• 出版日期2006-7-25