Polymers  Elmhurst College
Addition Polymers Rubber  Chemistry Department
Condensation Polymers Silicone    Virtual ChemBook

Condensation Polymers

Polyesters:

Polyesters such as PET (polyethylene terephthalate) are condensation polymers. The formation of a polyester follows the same procedure as in the synthesis of a simple ester. The only difference is that both the alcohol and the acid monomer units each have two functional groups - one on each end of the molecule. In this polymer, every other repeating unit is identical.

PET is made from ethylene glycol and terephthalic acid by splitting out water molecules (-H from alcohol and -OH from acid as shown in red on the graphic). The units are joined to make the ester group shown in green.

A simple representation is -[A-B-A-B-A-B]-.

Depending upon the processing a variety of products are possible. If cross linked it is made into clear plastic soft drink bottles. It can also be made into textile fibers known as Dacron and accounts for 50% of all fibers used to make clothing. Blended with cotton, Dacron is made into no-iron clothes.

This same polymer with the trade name of mylar when made as "tape" is magnetically coated for use in tape recorders and videotape machines.

Link to Polyester - with Chime molecule - Macrogalleria at U. Southern Mississippi

Polyamides - Nylon:

Polyamides such as nylon are also condensation polymers. The formation of a polyamide follows the same procedure as in the synthesis of a simple amide. Again, the only difference is that both the amine and the acid monomer units each have two functional groups - one on each end of the molecule. In this polymer, every other repeating unit is identical.

Nylon is made from 1,6-diaminohexane and adipic acid by splitting out water molecules (-H from the amine and -OH from acid as shown in red on the graphic). The units are joined to make the ester group shown in green.

A simple representation is -[A-B-A-B-A-B]-.

Nylon 66, discovered in 1931 by Wallace Cruthers at DuPont was the first completely synthetic fiber produced. It was introduced to women in nylon stockings in 1939 to immediate success. During World War II, nylon production went into making parachutes and other items needed by the military.

Nylon is very similar to the protein polyamides in silk and wool, but is stronger. more durable, more chemically inert, and cheaper to produce than the natural fibers.

See the Nylon demonstration below.

Link to Nylon - with Chime molecule - Macrogalleria at U. Southern Mississippi

 

Polyurethane:

Polyurethanes are made from a dialcohol and diisocyanate monomers. The isocyanate compounds contain the functional group (O=C=N-). A rearrangement reaction leads to the formation of the urethane linkage. Technically polyurethane is not a condensation polymer since no molecules are lost, but the functional group does rearrange.

A hydrogen moves from the alcohol to the nitrogen, while the oxygen links to the carbon. The urethane functional groups are similar to the amide group. In some applications the urethane polymer chains are further reacted to make cross links. Think of a chain link fence to get the idea of cross linking chains together.

Poly urethane an be drawn into fibers used in upholstery. Soft polyurethane foam can be used as padding in furniture and mattresses, while rigid foam is used as insulation in buildings.

Link to Polyurethane - with Chime molecule - Macrogalleria at U. Southern Mississippi

Condensation type Polymers
Demonstrations with Polymers

Nylon
Polyurethane Foam