Visible Light-Induced Cationic Polymerization Using Fullerenes

Area of Science:

• Polymer Chemistry
• Materials Science
• Photochemistry

Background:

• Cationic polymerization is a crucial process for synthesizing polymers.
• Visible light-initiated polymerization offers advantages in control and safety.
• Fullerene derivatives have shown potential in photochemistry and materials applications.

Purpose of the Study:

• To develop a novel visible light-sensitive photoinitiator system for cationic polymerization.
• To investigate the use of fullerene derivatives (C60 and polystyrene-C60 adduct) in initiating polymerization.
• To explore the mechanism of photoinitiation under visible light.

Main Methods:

• Visible light irradiation (λ > 400 nm) of monomers in the presence of fullerene derivatives and oxidizing salts.
• Utilizing monomers such as cyclohexene oxide, iso-butyl vinyl ether, and N-vinylcarbazole.
• Investigating polymerization in bulk and chlorobenzene solutions.
• Correlating polymerization with optical absorption, free energy changes (ΔG), and proton scavenging studies.

Main Results:

• Successful initiation of cationic polymerization of various monomers using visible light.
• Demonstrated effectiveness of both bare C60 and polystyrene-C60 adduct as photoinitiators.
• Identified a mechanism involving exciplex formation, electron transfer, and generation of radical cations and Brønsted acid.

Conclusions:

• The developed photoinitiator system is efficient for visible light-induced cationic polymerization.
• Fullerene derivatives, in conjunction with oxidizing salts, provide a versatile platform for photoinitiation.
• The proposed mechanism provides insight into the radical cation and Brønsted acid-mediated polymerization process.