The Surprising Science of Plastics

Since they were first developed back in the 1930s, synthetic polymers, what we commonly call plastics, have revolutionized modern society, they can be found everywhere, from packaging and consumer goods to even the most challenging engineering applications. Their unique molecular structure is what makes polymers so special. It determines all of their macroscopic properties, like how they

behave at different temperatures and how they respond to applied stress. Understanding this structure is the key to mastering polymers. So, that's where we'll start. A polymer is a material made up of a collection of extremely long molecules, each of which is formed from a repeating pattern of a smaller molecular unit. The repeating unit is called a

myrr, the Greek word for part, and it's the fundamental building block of any polymer, which means multiple parts. The polymer shown here is polyethylene, probably the most widely used of all synthetic polymers. Its repeating myrr unit has two carbon atoms and four hydrogen atoms. Linking all of these together creates a long molecular chain that has

a backbone of carbon atoms joined together by single coalent bonds and side groups which in the case of polyethylene are all single hydrogen atoms. One polymer chain can contain hundreds of thousands of MRS and there might be 10 quintilion chains in a single gram of material. That's a one followed by 19 zeros. The structure of a polymer can be

represented by showing the myrr chemical structure enclosed in square brackets and using the subscript n to indicate that the unit is repeated. Here we can see polyethylene with its repeating MR unit consisting of carbon and hydrogen atoms. Polyropylene has a similar structure to polyethylene but with a CH3 side group. Polyvinyl chloride has a chlorine