Lõppemisreaktsioonid

Lõppemisreaktsioonid, also known as termination reactions, are a crucial part of many chemical processes, particularly polymerization. In the context of free radical polymerization, lõppemisreaktsioonid signify the cessation of chain growth. These reactions occur when two growing polymer radicals combine or disproportionate. Chain combination involves two growing radicals joining to form a single, longer polymer chain. This typically results in a polymer with a higher molecular weight. Disproportionation, on the other hand, involves the transfer of a hydrogen atom from one growing radical to another. This process leads to the formation of two polymer chains: one with a saturated end and the other with an unsaturated end. Both combination and disproportionation effectively terminate the radical activity, preventing further addition of monomer units. The relative prevalence of these two termination pathways can depend on factors such as the specific monomer, the reaction temperature, and the solvent used. Understanding lõppemisreaktsioonid is vital for controlling the molecular weight and molecular weight distribution of polymers, which in turn influences their physical and mechanical properties. Beyond polymerization, termination reactions can also refer to the final stages of other chemical reactions where reactants are consumed or side reactions lead to the deactivation of reactive intermediates.