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<p>Using the example of polymerization of 2-methylene-1,3-dioxepane and copolymerization with styrene, it was shown that the main chain-growth termination reaction in radical ring-opening polymerization of ketene acetals is the chain transfer to monomer. This feature determines not only the formation of polymers with low molecular weight, but also the weak dependence of molecular weight on polymerization conditions (temperature, initiator concentration). The value of the chain transfer to monomer constant <i>C</i><sub><i>M</i></sub> = (1.2–1.6) × 10<sup>–2</sup>, determined by the method of linearizing chain length distribution, is 2–3 orders of magnitude higher than that for polymerization of vinyl monomers (styrene, MMA, etc.). The degree of polymerization (Pn) corresponds to the equation Pn = 1/<i>C</i><sub><i>M</i></sub>.</p>

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Chain transfer to monomer – the main chain-growth termination reaction in radical ring-opening polymerization of ketene acetals

  • 期刊论文

  • 发表日期：

    2025年1月21日

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  • Mikhail Yu. Zaremski,
  • Elvin E. Aliev,
  • Elena V. Pukhanova,
  • Nataliya S. Goulioukina

摘要

Using the example of polymerization of 2-methylene-1,3-dioxepane and copolymerization with styrene, it was shown that the main chain-growth termination reaction in radical ring-opening polymerization of ketene acetals is the chain transfer to monomer. This feature determines not only the formation of polymers with low molecular weight, but also the weak dependence of molecular weight on polymerization conditions (temperature, initiator concentration). The value of the chain transfer to monomer constant CM = (1.2–1.6) × 10–2, determined by the method of linearizing chain length distribution, is 2–3 orders of magnitude higher than that for polymerization of vinyl monomers (styrene, MMA, etc.). The degree of polymerization (Pn) corresponds to the equation Pn = 1/CM.