Cationic polymerization is a type of chain-growth polymerization that involves the formation of positively charged ions, or cations, to initiate the reaction. This process typically occurs with monomers that have electron-rich double bonds, such as styrene or isobutylene. The cationic initiator, often a Lewis acid or a proton donor, reacts with the monomer to create a reactive cation that can add to other monomer units, forming long polymer chains. This method is widely used in the production of various materials, including adhesives, coatings, and rubber. Cationic polymerization is known for its ability to produce polymers with high molecular weights and specific properties, making it valuable in industries like plastics and automotive. The process can be sensitive to moisture and temperature, which can affect the polymerization rate and final product characteristics.