Polymerization-Induced Self-Assembly Using Visible Light Mediated Photoinduced Electron Transfer-Reversible...

Area of Science:

• Polymer Chemistry
• Materials Science
• Photochemistry

Background:

• Reversible addition-fragmentation chain transfer (RAFT) polymerization is a controlled radical polymerization technique.
• Photoredox catalysis offers a sustainable method for initiating polymerization using visible light.
• Self-assembled polymeric nanoparticles have applications in drug delivery, diagnostics, and nanotechnology.

Purpose of the Study:

• To investigate the use of a ruthenium-based photoredox catalyst for initiating RAFT dispersion polymerization under visible light.
• To explore the formation of various polymeric nanoparticle morphologies (spherical micelles, worm-like micelles, vesicles) via in situ self-assembly.
• To study the influence of reaction parameters on nanoparticle morphology and achieve temporal control over the polymerization process.

Main Methods:

• Visible light-mediated photoredox catalysis using ruthenium(II) tris(2,2'-bipyridine) dichloride (Ru(bpy)3Cl2).
• RAFT dispersion polymerization of oligo(ethylene glycol) methyl ether methacrylate and benzyl methacrylate.
• Investigation of reaction parameters: catalyst concentration, total solids content, and cosolvent addition.
• Online Fourier transform near-infrared (FTNIR) spectroscopy for monitoring and controlling the polymerization.

Main Results:

• Successful initiation of RAFT dispersion polymerization using visible light and a photoredox catalyst.
• In situ self-assembly of polymeric nanoparticles with tunable morphologies, including spherical micelles, worm-like micelles, and vesicles.
• Isolation of highly pure worm-like micelles facilitated by the formation of in situ gels.
• Demonstration of "ON/OFF" control over polymerization and nanoparticle morphology using FTNIR spectroscopy.

Conclusions:

• Visible-light-activated photoredox catalysis provides an efficient route for controlled RAFT dispersion polymerization.
• The study successfully demonstrates the formation of diverse self-assembled polymeric nanoparticle morphologies.
• Precise control over nanoparticle formation and morphology is achievable by tuning reaction parameters and utilizing "ON/OFF" polymerization control.