<P> Condensation polymers are any kind of polymers formed through a condensation reaction--where molecules join together--losing small molecules as byproducts such as water or methanol, as opposed to addition polymers which involve the reaction of unsaturated monomers . Condensation polymerization is a form of step - growth polymerization, is a process by which two molecules join together, resulting in loss of small molecules which are often water . The type of end product resulting from a condensation polymerization is dependent on Monomers with only one reactive group do not padlock a growing chain, and thus give end products with a lower molecular weight . Linear polymers are created using monomers with two reactive end groups and monomers with more than two end groups give three - dimensional polymers which are cross linked . Common condensation polymers include polyamides, polyacetals and Proteins . </P> <P> Dehydration synthesis often involves joining monomers with an - OH (hydroxyl) group and a freely ionized - H on either end (such as a hydrogen from the - NH in nylon or proteins). Normally, two or more different monomers are used in the reaction . The bonds between the hydroxyl group, the hydrogen atom and their respective atoms break forming water from the hydroxyl and hydrogen, and the polymer. Actually in this process two water molecules are released.As given below (n + n = 2n) </P> <P> Polyester is created through ester linkages between monomers, which involve the functional groups carboxyl and hydroxyl (an organic acid and an alcohol monomer). </P> <P> Nylon is another common condensation polymer . It can be manufactured by reacting di - amines with carboxyl derivatives . In this example the derivative is a di - carboxylic acid, but di - acyl chlorides are also used . Another approach used is the reaction of di - functional monomers, with one amine and one carboxylic acid group on the same molecule: </P>

What type of polymers have the ester functional group