Condensation Polymers

Polyesters:

Polyesters such as PET (polyethylene terephthalate) arecondensation polymers. The formation of a polyester follows thesame procedure as in the synthesis of a simple ester. The onlydifference is that both the alcohol and the acid monomer units eachhave two functional groups - one on each end of themolecule. In this polymer, every other repeating unit is identical.

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

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

Depending upon the processing a variety of products arepossible. If cross linked it is made into clear plastic soft drinkbottles. It can also be made into textile fibers known as Dacronand accounts for 50% of all fibers used to make clothing. Blendedwith 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 andvideotape machines.

Link to Polyester - with Chimemolecule - Macrogalleria at U. Southern Mississippi

Polyamides - Nylon:

Polyamides such as nylon are also condensation polymers. Theformation of a polyamide follows the same procedure as in thesynthesis of a simple amide. Again, the only difference is thatboth the amine and the acid monomer units each have twofunctional groups - one on each end of the molecule. In thispolymer, every other repeating unit is identical.

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

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

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

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

See the Nylon demonstration below.

Link to Nylon - with Chimemolecule - Macrogalleria at U. Southern Mississippi

Polyurethane:

Polyurethanes are made from a dialcohol and diisocyanatemonomers. The isocyanate compounds contain the functional group(O=C=N-). A rearrangement reaction leads to the formation of theurethane linkage. Technically polyurethane is not a condensationpolymer since no molecules are lost, but the functional group doesrearrange.

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

Poly urethane an be drawn into fibers used in upholstery. Softpolyurethane foam can be used as padding in furniture andmattresses, while rigid foam is used as insulation in buildings.

Link to Polyurethane -with Chime molecule - Macrogalleria at U. SouthernMississippi