Aqueous SARA ATRP using Inorganic Sulfites.

Area of Science:

• Polymer Chemistry
• Macromolecular Science
• Green Chemistry

Background:

• Atom Transfer Radical Polymerization (ATRP) is a powerful controlled polymerization technique.
• Traditional ATRP often requires organic solvents and high catalyst concentrations.
• Developing environmentally friendly and efficient ATRP methods in aqueous media is highly desirable.

Purpose of the Study:

• To develop and optimize a novel aqueous SARA ATRP method utilizing inorganic sulfites.
• To achieve controlled polymerization of poly[oligo(ethylene oxide) methyl ether acrylate] (POEOA) with low copper catalyst concentration.
• To demonstrate the versatility of this method for chain extension, block copolymerization, and bioconjugation.

Main Methods:

• Investigated aqueous SARA ATRP using inorganic sulfites (e.g., Na2S2O4) as both activator and reducing agent.
• Optimized reaction parameters including ligand (TPMA), halide salts, sulfite feeding rate, and catalyst concentration.
• Characterized polymer properties including molecular weight, molecular weight distribution (Đ), and chain-end functionality.
• Performed one-pot chain extension, block copolymerization, and synthesis of protein-polymer hybrids.

Main Results:

• Achieved well-controlled POEOA synthesis with low soluble copper catalyst (<30 ppm) and narrow molecular weight distributions (Đ ~1.2).
• Demonstrated fast polymerization rates with linear first-order kinetics and linear molecular weight evolution up to ~80% conversion.
• Successfully performed "one-pot" chain extension and block copolymerization, indicating high chain-end fidelity.
• Synthesized a well-defined protein-polymer hybrid under biologically relevant conditions.

Conclusions:

• Aqueous SARA ATRP using inorganic sulfites is a highly effective method for controlled polymerization in water.
• This method offers advantages such as low catalyst loading, fast reaction rates, and excellent control over polymer architecture.
• The developed technique is versatile and applicable to synthesizing complex polymer structures and bioconjugates.