Polüondensatsiooni

Polüondensatsioon is a type of step-growth polymerization. It involves the reaction of monomers that possess at least two functional groups, where the reaction between these monomers results in the formation of a polymer chain and a small molecule byproduct. This byproduct is typically water, but can also be methanol, hydrogen chloride, or other small molecules. Unlike addition polymerization, which involves the direct joining of monomers without the loss of any atoms, polycondensation reactions involve the elimination of a small molecule during each bond-forming step.

The process can be visualized as a series of consecutive reactions. Initially, monomers react to form dimers, then trimers, and so on, with the gradual release of the small molecule. The molecular weight of the polymer increases incrementally as more monomers and oligomers react. Key characteristics of polycondensation include the requirement for monomers with specific reactive functional groups, such as hydroxyl (-OH), carboxyl (-COOH), amine (-NH2), and halide (-X) groups. The rate of polymerization is dependent on factors like temperature, catalyst concentration, and the concentration of the functional groups. Common examples of polymers formed by polycondensation include polyesters, polyamides (like nylon), polycarbonates, and polyurethanes. The properties of the resulting polymer are strongly influenced by the nature of the repeating monomer units and the functional groups involved in the condensation.