Abstract

Herein, we report a photoinitiated reversible addition-fragmentation chain transfer (RAFT) dispersion copolymerization of methyl methacrylate (MMA) and methyl methacrylic (MAA) for the preparation of highly monodisperse carboxyl-functionalized polymeric microspheres. High rates of polymerization were observed, with more than 90% particle yields being achieved within 3 h of UV irradiation. Effects of reaction parameters (e.g., MAA concentration, RAFT agent concentration, photoinitiator concentration, and solvent composition) were studied in detail, and highly monodisperse polymeric microspheres were obtained in most cases. Finally, silver (Ag) composite microspheres were prepared by in situ reduction of AgNO3 using the carboxyl-functionalized polymeric microspheres as the template. The obtained Ag composite microspheres were able to catalyze the reduction of methylene blue (MB) with NaBH4 as a reductant.

Highlights

  • Micron-sized polymeric microspheres have attracted much attention due to their broad applications in catalysis, molecular separation, molecular imprinting, Pickering emulsion, and biomedical analysis [1,2,3,4,5,6]

  • We focused on the preparation of monodisperse carboxyl-functionalized poly(methyl methacrylate) (PMMA) microspheres via photoinitiated reversible addition-fragmentation chain transfer (RAFT) dispersion copolymerization of MMA

  • This RAFT dispersion polymerization just focuses on the synthesis of polymer nano-objects with different morphologies rather than monodisperse polymeric microspheres [23,24,25,26,27,28,29,30,31,32]

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Summary

Introduction

Micron-sized polymeric microspheres have attracted much attention due to their broad applications in catalysis, molecular separation, molecular imprinting, Pickering emulsion, and biomedical analysis [1,2,3,4,5,6] These polymeric microspheres are most commonly prepared using the seeded swelling method developed by Ugelstad [7] or the seeded emulsion polymerization developed by Vanderhoff [8]. The Winnik group [14,16,17,18] developed a two-stage dispersion polymerization method for the synthesis of monodisperse functional polymeric microspheres (e.g., carboxyl-functionalized, cross-linked, reactive) with functional reagents added in the particle growth stage. We focused on the preparation of monodisperse carboxyl-functionalized poly(methyl methacrylate) (PMMA) microspheres via photoinitiated RAFT dispersion copolymerization of MMA and MAA. The carboxyl-functionalized polymeric microspheres prepared by the photointiated RAFT dispersion polymerization can be employed as templates for the synthesis of silver (Ag) composite microspheres

Materials
Characterization
Photoinitiated RAFT Dispersion Polymerization of MMA and MAA
Synthesis of Ag Composite Microspheres
Photoinitiated RAFT Dispersion Copolymerization of MMA and MAA
Effect of Photoinitiator
Effect of Stabilizer Concentration
Effect of Solvent Composition
Quantification of Carboxyl Groups on the Particle Surface
Conductometric
Conclusions
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