AIBN

2,2'-Azobis(isobutyronitrile), commonly abbreviated as AIBN, is an azo compound used as a thermal free-radical initiator in polymerization. When heated, the azo bond cleaves homolytically to produce two radical species derived from isobutyronitrile, with nitrogen gas released as a benign byproduct. These radicals initiate vinyl polymerization by adding to monomer double bonds, forming growing polymer chains.

AIBN is favored in many radical polymerizations because it decomposes cleanly at relatively moderate temperatures and generates radicals efficiently. It is employed in solution, bulk, and suspension polymerizations and is compatible with a range of monomers such as styrene, acrylates, methacrylates, and vinyl esters. The rate of initiation depends on temperature and solvent, with a typical half-life around 10 hours at 65°C, becoming faster at higher temperatures. It is soluble in common organic solvents like benzene, toluene, acetonitrile, and chlorinated solvents, and has limited solubility in water.

Safety and handling considerations are important when using AIBN. It can pose hazards due to its explosive potential when concentrated or subjected to shock or high heat; it should be stored away from heat sources, oxidizers, and mechanical shock, used in a fume hood, and handled according to relevant safety data sheets. Decomposition byproducts are primarily nitrogen gas, but care should be taken to avoid conditions that could lead to hazardous accumulations or rapid exothermic events.