Controlled polymerization is a method used to create polymers with specific properties and structures. This technique allows chemists to regulate the growth of polymer chains, resulting in materials with predictable molecular weights and narrow molecular weight distributions. By controlling the reaction conditions, such as temperature and concentration, researchers can tailor the final product for various applications. One common type of controlled polymerization is living polymerization, which enables the continuous growth of polymer chains without terminating reactions. This approach is beneficial for producing block copolymers and other complex structures, making it essential in fields like materials science and drug delivery.