Polükondensatsioon

Polükondensatsioon is a type of step-growth polymerization where monomers react to form a polymer with the elimination of a small molecule, such as water, methanol, or hydrogen chloride. This process differs from chain-growth polymerization, where monomers add sequentially to a growing chain. In polükondensatsioon, the reaction proceeds through a series of discrete steps, with each step involving the formation of a new bond and the release of a byproduct.

The monomers involved in polükondensatsioon typically contain two or more functional groups that can react with each other. For example, dicarboxylic acids can react with dialcohols to form polyesters, with the elimination of water. Similarly, diamines can react with diacids to form polyamides, also with the elimination of water. The rate of polükondensatsioon is generally slower than chain-growth polymerization, and the molecular weight of the polymer increases gradually throughout the reaction.

The resulting polymers from polükondensatsioon often possess strong intermolecular forces due to the presence of polar functional groups, leading to high melting points and good mechanical strength. Common examples of polymers formed through polükondensatsioon include polyesters, polyamides (like nylon), polycarbonates, and phenolic resins. The control over reaction conditions, such as temperature, concentration, and catalyst, is crucial for achieving desired molecular weights and properties in polükondensatsioon.