Polymerisationsverfahren

Polymerisation is the chemical process of linking monomer units to form polymer chains. The resulting materials, polymers, can have a wide range of properties and applications, depending on the monomer structure and the polymerisation method. Polymerisations are generally classified as addition (chain-growth) polymerisations or condensation (step-growth) polymerisations.

Addition polymerisation involves monomers with unsaturated bonds. The process proceeds via initiation, where active centers are generated; propagation, where the active center adds successive monomer units; and termination, where the growing chain finishes. Initiators include free radicals, cations, or anions; catalysts such as metallocenes or Ziegler-Natta systems enable controlled polymerisation and stereoregularity. Living polymerisation is a subset in which chain ends remain active, allowing precise control of molecular weight and architecture.

Condensation polymerisation involves monomers with two or more functional groups, and polymer chains form with the concurrent elimination of small molecules such as water or methanol. Examples include polyesters, polyamides, and polyurethanes. Condensation can proceed to high molecular weights, but removal of the condensate and stoichiometric balance influence the rate and degree of polymerisation.

Kinetics and properties: The molecular weight, tacticity, and architecture of polymers depend on monomer functionality, stoichiometry, temperature, solvent, and initiator or catalyst concentrations. Polymers exhibit distributions of chain lengths and can be linear, branched, or crosslinked, affecting mechanical, thermal, and rheological properties.

Applications and considerations: Polymers underpin plastics, textiles, coatings, and biopolymers. Industrial polymerisations emphasize safety, efficiency, and environmental sustainability, with attention to energy use, emissions, recyclability, and end-of-life management.