Polymers

3 Pages 681 Words

Tiny molecules strung in long repeating chains form polymers. Why should you care? Well for one thing, your body is made of them. DNA, the genetic blueprint that defines people and other living things, is a polymer. So are the proteins and starches in the foods we eat, the wheels on our skateboards and in-line skates, and the tires on our bikes and cars. In fact, we are surrounded by polymers, everywhere we go.
There’s another great reason to learn about polymers. Understanding their chemistry can help us use them wisely. Once we’re familiar with the varieties of polymers that people make, such as plastics, we can recycle many of them and use them again. That’s good for the environment
Although the fundamental property of bulk polymers is the degree of polymerization, the physical structure of the chain is also an important factor that determines the macroscopic properties.
The terms configuration and conformation are used to describe the geometric structure of a polymer and are often confused. Configuration refers to the order that is determined by chemical bonds. The configuration of a polymer cannot be altered unless chemical bonds are broken and reformed. Conformation refers to order that arises from the rotation of molecules about the single bonds. These two structures are studied below.
The two types of polymer configurations are cis and trans. These structures cannot be changed by physical means (e.g. rotation). The cis configuration arises when substituent groups are on the same side of a carbon-carbon double bond. Trans refers to the substituents on opposite sides of the double bond.

Stereo-regularity is the term used to describe the configuration of polymer chains. Three distinct structures can be obtained. Isotactic is an arrangement where all substituents are on the same side of the polymer chain. A syndiotactic polymer chain is composed of alternating groups and atactic is a random combination of the groups. ...