Condensation polymers and condensation polymerization reactions are very common in industry and in biological systems.

Condensation polymerization reactions are characterized by two monomers reacting to produce a polymer and another small molecule, usually water.

Condensation polymers can be natural or synthetic.

1. Synthetic Condensation Polymers

   
   Polyester is an example of a synthetic polymer that is formed through the process of condensation polymerization. In this particular reaction, a carboxylic acid reacts with an alcohol group to from an ester linkage. Because both the alcohol and the carboxylic reactants have two functional groups, this reaction can be repeated to create a long chain that consists of many esters joined together.

   
   
   
   

2. Natural Condensation Polymers

   
   Proteins are an example of a natural polymer that is formed through the process of condensation polymerization.

   
   Two amino acids can link together form a dipeptide.

   
   
   
   

   
   A polymer known as a polypeptide forms when amino acids (monomers) link together in long chains, as shown below:
   
   
   
   
   
   
   Starch is another example of a natural polymer that is formed through the process of condensation polymerization.  Starch is formed when many  glucose monomers link together.
   

   
   

Check Your Understanding

Complete "Practice" questions 12-13 on page 452 of the textbook.

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