Question

in stepwise polymerization _____ are obtained by the condensation of a dynamic with a dicarboxylic acid​

Answer 1

Answer:

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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. polyesters, polyamides, polyurethanes, etc. Due to the nature of the polymerization mechanism, a high extent of reaction is required to achieve high molecular weight. The easiest way to visualize the mechanism of a step-growth polymerization is a group of people reaching out to hold their hands to form a human chain—each person has two hands (= reactive sites). There also is the possibility to have more than two reactive sites on a monomer: In this case branched polymers production take place.

A generic representation of a step-growth polymerization. (Single white dots represent monomers and black chains represent oligomers and polymers)[1]

Comparison of molecular weight vs conversion plot between step-growth and living chain-growth polymerization

IUPAC deprecates the term step-growth polymerization and recommends use of the terms polyaddition, when the propagation steps are addition reactions and no molecules are evolved during these steps, and