Koordineerimispolümerisatsioon

Koordineerimispolümerisatsioon is a type of chain-growth polymerization where the monomer adds to a growing polymer chain with the assistance of a catalyst, often a transition metal complex. This process is distinct from other polymerization mechanisms like free-radical or ionic polymerization due to the crucial role of the catalyst in activating the monomer and directing the polymerization.

The mechanism typically involves the coordination of the monomer to the active center of the catalyst. This coordination is often followed by insertion of the monomer into the metal-carbon bond of the growing polymer chain. The catalyst then remains at the growing chain end, ready to coordinate and insert the next monomer molecule. This controlled insertion process allows for a high degree of stereoregularity in the resulting polymer, meaning that the arrangement of monomer units along the chain can be precisely controlled.

Key catalysts used in coordineerimispolümerisatsioon include Ziegler-Natta catalysts, which are typically a combination of a transition metal compound (like titanium tetrachloride) and an organoaluminum co-catalyst. Metallocene catalysts are another important class, featuring a transition metal sandwiched between two cyclopentadienyl rings. These catalysts have revolutionized the production of polyolefins, such as polyethylene and polypropylene, enabling the synthesis of polymers with tailored properties like high density, stiffness, and clarity. The ability to control polymer microstructure is a significant advantage of this polymerization method.