Madhusha is a BSc (Hons) graduate in the field of Biological Sciences and is currently pursuing for her Masters in Industrial and Environmental Chemistry. including polyesters, polyethers, 2. Web. A polymer chain is formed at the beginning by the attachment of one monomer at a time. The steps of chain polymerization include. 1. The end groups of the oligomers and polymers are later combined together, forming the polymer chain. The monomers in this case have two reactive groups. Polymers are giant molecules made of small units known as monomers. The other process, called step-growth polymerization, involves the build-up of molecular weight not in a chainlike fashion but in a stepwise fashion, by the random combination of monomer molecules containing reactive functional groups. Step Growth Polymerization: In step growth polymerization, all the monomers are active themselves. Step-growth polymerization refers to a type of polymerization mechanism in which bi-functional or multifunctional monomers react to form first dimers, then trimers, longer oligomers and eventually long chain polymers.Many naturally occurring and some synthetic polymers are produced by step-growth polymerization, e.g. is, polymer, oligomer and monomer can react with any other molecule. In order to achieve high molecular weight reaction(s) between monomers(s) and active site(s) on the polymer chain with In step growth polymerization, monomers exist through the reaction, In a CHAIN-GROWTH polymerization, only ‘initiated’ monomers (or the growing chain) can react. regeneration of the active site(s) at the end of each growth step. the reaction. Average molecular weight increases slowly at low Chain growth system The characteristic of a chain polymer is that polymer growth takes place by monomer reacting only with the reactive centers . Molar mass of backbone chain increases rapidly N.p., n.d. Now the differences between a chain growth polymerization and a step growth polymerization are a little more complicated than the differences between an addition polymerization and a condensation polymerization. Chain Growth Polymerization: Chain growth polymerization shows no growth of polymer chain after termination. The main difference between chain growth polymerization and step growth polymerization is that the chain growth polymerization involves the growth a polymer chain at its ends whereas the step growth polymerization involves the combination of oligomers to form a polymer chain. oligomer and monomer can react with any other molecule. There are normally two distinctive mechanisms during polymerization, CHEM 379 – W20 Polymers & Polymerization 5-14 Due to this reaction pattern, the chain length increases linearly with time in a step-growth polymerization reaction, as shown here. Different steps operate at different stages of mechanism. polyacrylonitrile, polyvinyl acetate etc. 1. Nylon-6,6 is formed by step-growth polymerization. include initiation, propagation, termination and chain transfer. 2.2. In chain addition polymerization, only monomers Introduction: step-growth vs. chain growth polymerization. Then these oligomers combine with each other forming long polymer chains. It goes something like this: In a chain growth polymerization, monomers become part of the polymer one at a time. According to the initiator used in the chain growth polymerization process, there are three types of chain growth polymerization. approximately   the same throughout the In contrast to chain-growth, all monomers are reactive. Step growth polymerization has oligomers instead of polymer chains at the beginning because the monomers involved in this process are composed of at least two different functional groups. Libretexts. 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