livingpolymerointimenetelmät

Living polymerization is a type of chain-growth polymerization where chain termination and chain transfer reactions are suppressed or eliminated. This controlled nature allows for the synthesis of polymers with well-defined molecular weights, narrow molecular weight distributions (low polydispersity), and predictable architectures. In living polymerization, all polymer chains initiate at approximately the same time and grow at a similar rate. This means that when the monomer is consumed, the active chain ends remain capable of re-initiation if more monomer is added.

Several methods fall under the umbrella of living polymerization. These include anionic polymerization, cationic polymerization, radical polymerization, and coordination polymerization. Anionic and cationic living polymerizations are often achieved by using specific initiators and reaction conditions that prevent chain termination. Living radical polymerization (LRP) techniques, such as nitroxide-mediated polymerization (NMP), atom transfer radical polymerization (ATRP), and reversible addition-fragmentation chain transfer (RAFT) polymerization, have revolutionized the control over free radical processes, which were traditionally notorious for their lack of control. These LRP methods utilize reversible deactivation of the propagating radicals to maintain a low concentration of active species, thereby minimizing termination events.

The ability to control polymer architecture through living polymerization opens doors to synthesizing block copolymers, star polymers, and graft copolymers. These complex macromolecular structures are valuable in various applications, including drug delivery, nanotechnology, advanced materials, and coatings. The precise control over chain length and composition is critical for tailoring the material properties to specific end-uses.