astmelispolümerisatsioon

Astmelispolümerisatsioon, also known as step-growth polymerization, is a type of polymerization mechanism where monomers react with each other in a stepwise manner to form larger molecules. Unlike chain-growth polymerization, where a chain reaction is initiated and propagated rapidly, astmelispolümerisatsioon involves the gradual formation of dimers, trimers, and oligomers, which then further react to form long polymer chains. This process typically involves bifunctional or multifunctional monomers.

The reaction often proceeds through condensation reactions, where a small molecule, such as water or methanol, is eliminated with each bond formation between monomers. Common examples of polymers formed by astmelispolümerisatsioon include polyesters, polyamides, and polyurethanes. The molecular weight of the polymer increases throughout the reaction, and high molecular weights are generally achieved only when the conversion of monomers is very high.

Key characteristics of astmelispolümerisatsioon include a slow reaction rate at the beginning, a period of rapid molecular weight increase, and a gradual build-up of high molecular weight as the reaction nears completion. The process can be controlled by factors such as temperature, catalyst concentration, and monomer purity. The resulting polymers often exhibit distinct properties based on the specific monomers and reaction conditions employed.