Kinetic parameters for thermal decomposition of commercially available dialkyldiazenes (IUPAC Technical Report)

This report provides a summary of recommended or suggested values of the rate coefficients for thermal decomposition ( k d ) and of the efficiencies for radical generation ( f g ) and initiation of polymerization ( f i ) for some commercially available dialkyldiazene (also known as azo-compound) initiators. These initiators are one of the most important classes of initiators used in both conventional radical polymerization and reversible-deactivation radical polymerization (RDRP). Although values of k d can be cited with confidence for many initiators, it must also be stated that for most initiators there is insufficient quality data in the open literature to allow a rigorous statistical analysis. The situation is complicated by some initiators existing as a mixture of diastereomers and decomposition rates being subject to small, yet experimentally significant, solvent dependence. Efficiencies for radical generation ( f g ) are available for some initiators. Efficiencies for initiation of polymerization ( f i ) are less common and have been demonstrated to be strongly dependent on the initiator, the complexity of the mechanisms for radical generation and for initiation of polymerization, the reaction medium, the monomers being polymerized and their concentration as determined by the amount of solvent, and the conversion of monomer to polymer. Consequently, only general recommendations for initiator efficiency are possible at this stage.