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<p>Ring-opening polymerization of L,L-lactide (LA) was carried out at 160&#xa0;°C in bulk using methoxy poly(ethylene glycol) (mPEG) as a macroinitiator and stannous octoate (Sn(Oct)<sub>2</sub>) as a catalyst. To evaluate the effect of macroinitiator content on polymerization behavior, the [LA]/[mPEG] molar ratio was varied from 15 to 120 at a constant [LA]/[Sn(Oct)<sub>2</sub>] ratio. The polymerization is consistent with an alcohol-assisted coordination-insertion mechanism with efficient initiation from mPEG hydroxyl end-groups. Decrease of the [mPEG]/[Sn(Oct)<sub>2</sub>] ratio resulted in a pronounced acceleration of polymerization, reducing the time required to reach high conversion from ~ 30&#xa0;h to &lt; 1&#xa0;h. Apparent pseudo-first-order kinetic behavior was observed in the linearized kinetic plots, with apparent propagation rate constants increasing from 1.4·10<sup>− 3</sup> to 6.2·10<sup>− 2</sup> min<sup>− 1</sup>. The molecular structure and end-group fidelity were confirmed by size exclusion chromatography (SEC), <sup>1</sup>H and 2D nuclear magnetic resonance (NMR) spectroscopy. The resulting block copolymers exhibited predictable P(L)LA block lengths close to the targeted values, along high conversion (≥ 91%) and low dispersity (Đ = 1.10–1.28).</p> Graphical abstract <p></p>

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Controlled synthesis of poly(L,L-lactide)-block-polyethylene glycol: polymerization kinetics and molecular structure of the polymers

  • 期刊论文

  • 发表日期：

    2026年6月15日

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  • Yulia A. Puchkova,
  • Nikita G. Sedush,
  • Valeria A. Ivanova,
  • Alexander M. Perepukhov,
  • Timur N. Bozin,
  • Alexander I. Buzin,
  • Sergei N. Chvalun

摘要

Ring-opening polymerization of L,L-lactide (LA) was carried out at 160 °C in bulk using methoxy poly(ethylene glycol) (mPEG) as a macroinitiator and stannous octoate (Sn(Oct)2) as a catalyst. To evaluate the effect of macroinitiator content on polymerization behavior, the [LA]/[mPEG] molar ratio was varied from 15 to 120 at a constant [LA]/[Sn(Oct)2] ratio. The polymerization is consistent with an alcohol-assisted coordination-insertion mechanism with efficient initiation from mPEG hydroxyl end-groups. Decrease of the [mPEG]/[Sn(Oct)2] ratio resulted in a pronounced acceleration of polymerization, reducing the time required to reach high conversion from ~ 30 h to < 1 h. Apparent pseudo-first-order kinetic behavior was observed in the linearized kinetic plots, with apparent propagation rate constants increasing from 1.4·10− 3 to 6.2·10− 2 min− 1. The molecular structure and end-group fidelity were confirmed by size exclusion chromatography (SEC), 1H and 2D nuclear magnetic resonance (NMR) spectroscopy. The resulting block copolymers exhibited predictable P(L)LA block lengths close to the targeted values, along high conversion (≥ 91%) and low dispersity (Đ = 1.10–1.28).

Graphical abstract