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Miniemulsion Ring-Opening Radical Polymerization with Dibenzo[c,e]oxepan-5-thione for Degradable Polymer Particles

ACS Applied Polymer Materials 2025 1 citation ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Kaoru Fuji, Yukiya Kitayama, Atsushi Harada

Summary

Researchers developed a new technique to synthesize degradable polymer particles using a process called radical ring-opening polymerization in a miniemulsion system, incorporating a ring-opening monomer that introduces ester-thioester bonds into the polymer backbone. The resulting particles broke down when exposed to amine compounds, unlike conventional plastic particles that persist in the environment. This approach offers a potential path toward designing plastic materials that can degrade after use, reducing the generation of persistent microplastics from industrial and consumer products.

Polymer-based particulate materials are useful in various industries, but nondegradable polymeric particulate materials that generate microplastics pose challenges. Herein, we synthesized main-chain degradable polymer particles by radical ring-opening polymerization (rROP) in a miniemulsion system (miniemulsion rROP), in which dibenzo[c,e]oxepan-5-thione (DOT) was selected as the ring-opening monomer. Miniemulsion rROP of DOT and typical vinyl comonomers (styrene: St and n-butyl acrylate: nBA) was performed. The polymerization rate of the miniemulsion rROP was significantly higher than that of solution rROP. The DOT feed molar ratio in the miniemulsion rROP was increased to 20 mol % with high conversion. Colloidally stable poly(St-DOT) particles were successfully synthesized and were degraded by amine compounds in homogeneous and heterogeneously dispersed systems. Additionally, when nBA was used as the vinyl monomer, colloidally stable main-chain degradable poly(nBA-DOT) particles were successfully synthesized, and their degradation was observed with n-propylamine, evidencing the possibility of using miniemulsion rROP to synthesize degradable polymer particles.

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