Ring Formation in Step-Growth Polymerization

Step growth polymerizations can be complicated by cyclization reactions that accompany formations of linear polymers. Such ring formations can occur in reactions of monomers with either the same type of functional groups or with different ones. Following are some illustrations of cyclization reactions  

Similarly, dicarboxylic acids can cyclize into anhydrides. 

It was reported that at least in one instance, the products of a reaction can be affected by the isomer used [244], Thus, in the following Knoevenagel condensation, a polymer will form when an ortho isomer is being reacted  

By contrast, the meta isomer forms only ring structures instead [242]  

7 Step-Growth Polymerization and Step-Growth Polymers 

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