livingpolymerization

Living polymerization is a type of chain-growth polymerization where the active propagating chain ends remain capable of further growth indefinitely. This means that termination and irreversible chain transfer reactions are essentially absent during the polymerization process. The key characteristic of a living polymerization is that all polymer chains are initiated at approximately the same time and grow at a similar rate.

This controlled growth allows for precise control over the molecular weight, molecular weight distribution (which is typically very narrow, often described by a low dispersity index, Ð), and polymer architecture. Because the chain ends remain active, it is possible to add more monomer to a completed living polymer solution and have it reinitiate polymerization, extending the chain length. Furthermore, different monomers can be added sequentially to create block copolymers with well-defined segments.

Living polymerization techniques include anionic polymerization, cationic polymerization, controlled radical polymerization (CRP) methods such as atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization, and nitroxide-mediated polymerization (NMP). These methods have revolutionized polymer synthesis, enabling the creation of complex macromolecular structures and materials with tailored properties for advanced applications in areas like drug delivery, nanotechnology, and advanced materials. The absence of termination steps is fundamental to achieving this level of control.