Do The Twist: Efficient Heavy-Atom-Free Visible Light Polymerization Facilitated by Spin-Orbit Charge Transfer...

Area of Science:

• Materials Science
• Organic Chemistry
• Photochemistry

Background:

• Visible light polymerization offers a milder alternative to UV-based methods for soft material production.
• Current visible light photoredox catalysis often relies on heavy atoms like precious metals or toxic halogens.

Purpose of the Study:

• To develop an efficient visible light polymerization method that avoids the use of heavy atoms.
• To investigate the mechanism of polymerization initiation using novel boron dipyrromethene (BODIPY) dyads.
• To demonstrate the application of this system in high-resolution 3D printing.

Main Methods:

• Synthesis of novel boron dipyrromethene (BODIPY) dyads with twisted aromatic groups.
• Visible light-initiated polymerization studies.
• Ultrafast transient absorption and phosphorescence spectroscopies to study reaction mechanisms.
• 3D printing experiments using a green LED light source.

Main Results:

• Achieved efficient visible light polymerization in the absence of heavy atoms via spin-orbit charge transfer intersystem crossing.
• Observed a significant increase in polymerization rate (≈5-15×) and improved photostability with twisted BODIPYs compared to controls.
• Demonstrated that monomer polarity influences polymerization rate, attributed to charge transfer stabilization.
• Successfully performed rapid and high-resolution 3D printing using the developed photosystem.

Conclusions:

• Twisted BODIPY dyads enable efficient, heavy-atom-free visible light polymerization.
• The developed system offers enhanced polymerization rates and photostability.
• This technology facilitates advanced 3D printing applications with improved control and resolution.