redoxinitiated

Redox-initiated refers to the initiation of chemical reactions, especially radical polymerization, through redox reactions between an oxidizing and a reducing component that generate radicals capable of starting chain growth. These systems enable polymerization at ambient temperatures and are used when heat-sensitive substrates must be preserved.

Common redox-initiated systems include ammonium persulfate with TEMED in aqueous media, where persulfate oxidizes TEMED to produce sulfate radicals that initiate polymerization of acrylamide or acrylate monomers. Another class uses organic peroxides such as benzoyl peroxide in combination with amines, enabling room-temperature curing of resins and adhesives. The specific choice of redox pair and solvent governs rate, final molecular weight, and degree of polymerization.

Mechanistically, the oxidant accepts electrons from the reductant, forming radical species that attack monomer double bonds to form growing polymer chains. Oxygen can quench these radicals, so processes are often conducted under inert conditions or with oxygen scavengers.

Applications include gel formation for electrophoresis, dental resins, coatings, and adhesives where room-temperature curing is advantageous. Advantages of redox initiation are rapid setting at ambient temperature and tunability through initiator concentrations, while drawbacks include sensitivity to oxygen, potential hazards from strong oxidants and amines, and possible variability in polymer properties if conditions are not carefully controlled.