vaihejpolimerisaation

Vaihejpolimerisaatio, also known as step-growth polymerization, is a method of polymer synthesis where monomers join together through sequential reactions to form longer chains. Unlike chain-growth polymerization, where monomers add rapidly to an active growing chain, in vaihejpolimerisaatio, the molecular weight of the polymer increases gradually throughout the reaction. This occurs because the reaction involves the formation of dimers, trimers, and larger oligomers before eventually forming high molecular weight polymers.

The key characteristic of vaihejpolimerisaatio is that any monomer can react with any other monomer, oligomer, or polymer molecule. This means that at any stage of the reaction, the mixture contains species of various molecular weights, and the average molecular weight increases slowly and steadily. The reaction typically involves bifunctional or polyfunctional monomers that possess reactive groups, such as hydroxyl, carboxyl, or amine groups. Common examples of polymers synthesized by vaihejpolimerisaatio include polyesters, polyamides (like nylon), and polyurethanes. The process can be initiated without a specific initiator, as the reaction often proceeds through self-condensation or reaction between different functional groups present in the monomers. Control over the reaction conditions, such as temperature and concentration, is crucial for achieving the desired molecular weight and polymer properties.