Ring-opening polymerization (ROP) is a kind of chain-growth polymerization used in the chemistry of polymers. During this process, the terminal of a polymer chain attacks cyclic monomers to create a longer polymer. An anionic, cationic, or radical reactive centre is possible. Metal catalysts can be used to polymerize certain cyclic monomers, such as norbornene or cyclooctadiene, into high molecular weight polymers. ROP is a flexible technique for creating biopolymers. The reduction of bond-angle strain frequently causes the rings of cyclic monomers to open. T Additionally, radical ROP may be used to create polymers with embedded functional groups that are otherwise impossible to create by regular chain-growth polymerization of vinyl monomers. For instance, radical ROP can create polymers having functional groups such as ethers, esters, amides, and carbonates.