Reactions in Condensation Polymers

Similar interchange processes may occur in other condensation polymers under suitable conditions. There is ample evidence in the literature on polyamides, and on monomeric amides as well, for the occurrence of the amine-amide interchange reaction (II) 

The counterpart of reaction (III) in polyesters, i.e., ester-ester interchange, probably does not take place to any appreciable degree. Polymeric polysulfide rubbers ( Thiokor type) 

Polyanhydrides are susceptible to interchange reactions with carboxyl groups in analogy to (I) and (II). Polymeric dimethylsiloxanes readily interchange in the presence of sulfuric acid by a mechanism which may be presumed to involve cations. In some polymers the interunit linkage is too stable to enter readily into interchange reactions. Such an example is polyethylene oxide 

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Redistribution during thermal processing is a common self-reaction in condensation polymers such as PA, PEST, and PC that often contain nucleophilic amine, hydroxy, or phenolic end-groups, along with electrophilic groups such as amide, ester, or carbonate linking the individual monomer units. 

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