Chemistry of Polymerization (Part 2)  || Step Growth Polymerization || UG PaathShaala
Channel: PaathShaaala
Date: 23/03/2021

A step-growth polymerization is a stepwise reaction between the same or different monomers which contains two or more functional groups like hydroxyl, carboxyl and amino groups. Many organic reactions can be involved in the step-growth polymerization like condensation, addition, ring-opening, amidation, etc. Step polymerization reactions mostly take place with the elimination of small molecules like H2O, HCl, alcohol, etc.
 Many natural and synthetic polymers are produced by step-growth polymerization including polyesters, polyethers, urethanes, epoxies, and polyamides involve polycondensation. For example, the reaction of dicarboxylic acids with diamines to form polyamides (Nylon) and the reaction of organic diacids with alcohols to form polyesters. Polyaddition is a reaction between functional groups of molecules such as dimers, trimers and oligomers without the co-generation of other products such as water or alcohol.
      In this type of polymerization method, monomers with di or multi-function groups are necessary at least to form a polymer. A difunctional monomer or equal molar amounts of two different difunctional monomers can form a linear high molecular weight polymer. In a step-growth polymerization, the molecular weight of the polymer chain builds up slowly and there is only one reaction mechanism for the formation of the polymer. The distinct initiation, propagation, and termination steps of chain-growth polymerization are not present in step-growth polymerization.