stepgrowthpolymerisaatioon

Step-growth polymerization is a method of polymer synthesis where monomers react with each other in a stepwise fashion to form longer polymer chains. This process typically involves the reaction of functional groups present on the monomers. Unlike chain-growth polymerization, where a chain is initiated and then grows by the rapid addition of monomers to the growing chain end, step-growth polymerization involves the reaction between any two molecules with appropriate functional groups, regardless of their size. This means that small oligomers and polymers of various lengths are present throughout the reaction, and the molecular weight of the polymer increases gradually as more and more monomer units are added to these growing chains. The reaction can proceed between monomers, between a monomer and an oligomer, or between two oligomers. Common examples of step-growth polymerization include the formation of polyesters, polyamides, and polyurethanes. These polymers are often formed through condensation reactions, where a small molecule like water or methanol is eliminated as a byproduct. The reaction rate is generally independent of molecular weight, meaning that the rate of reaction between two monomers is similar to the rate of reaction between two high molecular weight polymer chains. The molecular weight distribution in step-growth polymerization is typically described by the Flory-Schulz distribution.