Theoretical and Experimental Study of Light-assisted Polymerization by Multimechanism Action

Area of Science:

• Polymer Chemistry
• Materials Science
• Photochemistry

Background:

• Cobalt-based driers in alkyd systems pose health risks due to potential carcinogenicity.
• Developing safer alternatives for alkyd resin curing is crucial for industrial applications.

Purpose of the Study:

• To design a novel bicomponent alkyd system that minimizes cobalt drier usage.
• To investigate the synergistic effects of an air-sensitive cobalt drier and a light-sensitive photoinitiator on alkyd autoxidation.
• To elucidate the mechanism of photoassisted autoxidation in alkyd resins.

Main Methods:

• Real-time infrared spectroscopy to monitor autoxidation influenced by cobalt drier and isopropylthioxanthone.
• Linear free energy relationship to predict photoinitiator hydrogen abstraction ability.
• Nanosecond laser flash photolysis and Stern-Volmer equation to determine quenching rate constants.
• Quantum chemistry calculations and time-dependent density functional theory for thermodynamic and electronic properties.

Main Results:

• Isopropylthioxanthone enhances hydrogen abstraction efficiency at the onset of curing.
• Theoretical predictions of photoinitiator hydrogen abstraction ability align with experimental findings.
• A photoassisted autoxidation mechanism for alkyd resins was proposed based on experimental and theoretical data.

Conclusions:

• The novel bicomponent alkyd system effectively reduces reliance on cobalt driers.
• Visible light irradiation combined with a photoinitiator offers an efficient and safer alternative for alkyd resin curing.
• Understanding the photoassisted autoxidation mechanism provides a basis for developing advanced coating technologies.