Ring-Opening Polymerization of Cyclic Amides (Lactams)

The ring-opening polymerization (ROP) of lactams is extensively reviewed, covering all aspects related to their polymerizability, in terms of both thermodynamic feasibility and kinetic likeliness, with greater attention to the many different aspects of the anionic polymerization, also in terms of its industrial applications. Other polymerization mechanisms (e.g., cationic) or routes (e.g., enzymatic) are synthetically introduced and updated. Specific lactams (ε-caprolactam (CL), ω-laurolactam, 2-pyrrolidone, and C-substituted β-lactams) and their anionic polymerization are described in detail, with a mention of the living polymerization of the latter family of lactams. Anionic copolymers of the most relevant lactams are listed, with a description of the synthetic routes adopted for each pair.