Polümerisatsioonile

Polümerisatsioonile is the Estonian term for polymerization, a chemical process where small molecules called monomers combine to form long chains or networks of repeating units known as polymers. This reaction is fundamental to the creation of plastics, rubbers, and many other synthetic and natural materials. There are several distinct mechanisms by which polymerization can occur.

Chain-growth polymerization, also known as addition polymerization, involves monomers adding sequentially to an active site, typically an initiator molecule. This process is characterized by the rapid growth of polymer chains. Common examples include the polymerization of ethylene to polyethylene and the polymerization of vinyl chloride to polyvinyl chloride (PVC). Free radical, cationic, and anionic mechanisms are all types of chain-growth polymerization, differing in the nature of the active species that propagates the chain.

Step-growth polymerization, conversely, involves reactions between functional groups on monomers, oligomers, and polymers. The molecular weight of the polymer increases gradually as monomers and smaller chains react with each other. This type of polymerization often results in the formation of byproducts, such as water. Polyesters and polyamides, like nylon, are typically formed through step-growth polymerization.

Bulk, solution, suspension, and emulsion polymerization are common methods used to carry out these reactions, each with its own advantages and disadvantages regarding heat control, product purity, and viscosity. Understanding the specific type of polymerization and the conditions under which it occurs is crucial for controlling the properties of the resulting polymer, such as its molecular weight, branching, and tacticity, which in turn dictate its physical and chemical behavior.