Living Polymerization

Synthetic polymers are long chain molecules containing repeat units of monomers. The polymers can be prepared by free radical polymerization, condensation polymerization and by living polymerization. In a living polymerization, the molecular weight is directly proportional to conversion. Living polymerization techniques give the synthetic chemist two particular powerful tools for polymer chain design, the synthesis of block copolymers by sequential addition of monomers and the synthesis of functional ended polymers by appropriate reagents. In the anionic polymerization organic alkali – metal salts are most widely used initiators whereas in cationic polymerization most commonly used catalysts are metal trihalides such as AlCl3 or BF3. The first entirely aqueous living polymerization was catalyzed by metal complexes such as ruthenium biphosphine complexes containing a ruthenium carbon double bond.