Radikalpolymerisationen

Radikalpolymerization, or radical polymerization, is a class of chain-growth polymerization in which polymer chains grow by the successive addition of monomer units via carbon-centered radical active centers. The process is typically initiated by free radicals generated thermally, photochemically, or chemically (for example, from peroxides or azo compounds). After initiation, propagation adds monomer units to the growing radical, rapidly building macromolecules. Termination occurs by radical–radical combination or disproportionation, or by chain transfer to monomer, solvent, or impurities, which can cap the growing chain.

Monomers that participate include a wide range of vinyl compounds such as styrene, acrylates, methacrylates, and vinyl esters. The polymerization can be conducted in bulk, solution, suspension, emulsion, or other heterogeneous systems, leading to various particle sizes and morphologies. Oxygen inhibits radical polymerization, so deoxygenation or inert atmospheres are common for high conversions. Reaction rates depend on initiator concentration, temperature, light (in photoinitiated cases), and monomer concentration. Conventional radical polymerization often yields broad molecular weight distributions due to rapid termination events and chain-transfer reactions, influencing material properties.

Controlled or living radical polymerization methods (for example, RAFT, ATRP, and nitroxide-mediated polymerization) provide greater control over molecular weight and architecture, enabling block copolymers and well-defined structures, though they can require more stringent conditions and specialized reagents.

Applications are widespread, including coatings, adhesives, plastics, inks, dental resins, and hydrogels, reflecting the method’s versatility and robustness in producing diverse polymer materials.