Anioonpolümerisatsiooniks

Anioonpolümerisatsiooniks refers to anionic polymerization in Estonian. It is a type of chain-growth polymerization where the propagating species is an anion. This process requires monomers with electron-withdrawing groups that can stabilize the negative charge at the active center. Common monomers for anionic polymerization include vinyl monomers like styrene, butadiene, isoprene, and acrylates. The polymerization is typically initiated by strong bases, such as organometallic compounds (e.g., alkyllithiums), alkali metal amides, or alkoxides. The initiation step involves the nucleophilic attack of the initiator anion on the monomer, creating a new carbanion that can then propagate by adding more monomer units. Anionic polymerization is often carried out at low temperatures to minimize side reactions and achieve high molecular weights and narrow molecular weight distributions. A key characteristic of living anionic polymerization is the absence of chain transfer and termination reactions. This allows for precise control over the polymer architecture, including the synthesis of block copolymers and polymers with controlled end-group functionality. The termination can be achieved by adding a protic compound (e.g., water, alcohol) or an electrophilic reagent. This polymerization method is important for producing various synthetic rubbers, plastics, and specialty polymers with specific properties.