What Are Synthetic Polymers?
Check out these images of useful, everyday items. Do you notice anything that they have in common? For one, all these compounds are super strong, cheap, and easy to make. Secondly, they are all examples of this video's topic: synthetic polymers! But what is a synthetic polymer?
Let's break the term apart to discover the definition. To start, a compound that is synthetic is man-made and produced by chemical reactions. Synthetic compounds may be made as exact replicas of naturally occurring compounds like vitamin C, or they may be unique compounds like plastic.
To talk about polymers, imagine a paperclip chain. If you've got time (and lots of paperclips), you can just make one instead of thinking about it! A paperclip chain is like a polymer. It is a long, strong chain made of many paperclips hooked together. By definition, a polymer is a compound that is made of many small repeating units bonded together. In our case, the small repeating units are the paper clips.
We use the scientific term 'monomer' to describe the small, repeating units used to make up a polymer. Polymers usually consist of tens of thousands of monomers, all bonded together. Huge molecules like these are often referred to as macromolecules. Our world is loaded with naturally occurring polymers, like cellulose (the stuff in plant fibers), DNA (the molecule that contain our genes), and silk.
Now, we can put our two terms together! A synthetic polymer is a man-made macromolecule that is made of thousands of repeating units. Sometimes these polymers are straight-chained, like our paperclip chain example, and consist of one long chain of monomers bonded end to end.
Sometimes polymers are both straight-chained and branched. This means that neighboring chains will bond with each other and make vast, net-like structures. This type of bonding between chains is called crosslinking.
Synthetic polymers are lightweight, hard to break, and last a long time. They are quite cheap to make and easy to form into shapes.
One of the most common and versatile polymers is polyethylene. It is made from ethylene (also known as ethene) monomers. In polymer form, the double bond between the carbons is lost and a chain is formed between repeating units of two carbons, each bonded to two hydrogens.
Sometimes for brevity's sake, the polymer chain is represented like the image you see here, with a large pair of parentheses around the monomer. You'll notice that there is an n in the bottom right hand corner outside the parenthesis. This n can represent any number. It could be 5 or 10,000! Often times, it is just left as a simple n to show it is a polymer of varying length.
Polyethylene is used to make plastics of all sizes and shapes, from piping to bottles to toys. And if you've ever dealt with these pesky things, then you know polyethylene!
Polyethylene has a pretty popular cousin, named polyethylene terephthalate (abbreviated PET or PETE). You might recognize PET from our intro! PET is commonly used for packaging liquids, especially sodas. PET is also used to make plastics that need to tolerate extreme temperatures.
PET is a great example of a thermoplastic. Thermoplastics are solid until heated to a certain temperature. When they get to that special temperature, they can be molded into any shape. Once they cool, their shape is set. Thermoplastics can be melted down once they are used up or no longer needed, and reshaped! This process is known as recycling.
Maybe you've seen these symbols on some plastics? They tell you several things. First, the item is a thermoplastic. Also, the number represents the type of polymer. And lastly, this symbol lets you know that this is very recyclable! Next time you are using something in a plastic bottle, look for one of these symbols. Then when you're finished using the plastic bottle, make sure to recycle it