Playtime with Polymers
In previous weeks, you learned about atoms and molecules. Atoms join together to make larger particles called molecules. Different combinations of atoms make different types of molecules. Molecules have different sizes and shapes. In some cases, small molecules can join together and form molecular chains. These chains are called polymers.
Polymers are everywhere in everyday life, from the paint on the walls to the clothes you wear. All plastics are polymers. Most everyday polymers are flexible, smooth, light, and usually colorful. Can you see any polymers around you? Discuss this with your mentor.
In gases, the atoms or molecules are far apart and they do not stick together. In liquids, they are closer together, but they still move around and slide over each other. In solids, the atoms or molecules stick together and stay in one place.
The polymers we are going to make today have the properties of both liquids and solids. They can flow like a liquid, but you can hold them in you hand like a solid. The chains resist fast change. For instance, imagine putty. If you hit it hard, it doesn’t change much, but if you squish it between your fingers softly, it changes shape quite easily.
Today, you will experiment with two types of polymers: slime made out of detergent and glue, and cornstarch.
Goop
You will need:
· 2 tbsp cornstarch
· 2 tbsp water
· food coloring
Add a drop of food coloring to the water. Mix the colored water into the cornstarch. Have fun!
What happens to the goop when you press on it hard?
What happens when you let it sit in your hand?
Slime
You will need:
· 1 tbsp detergent
· glue
· food coloring
Add food coloring to the detergent. Mix glue into the detergent until it forms slime. Have fun!
Roll the slime into a ball and pull it apart gently. Roll it up again and pull hard. Which time did it break?
Questions
1. What is a polymer? Give an example of a polymer you use in everyday life.
2. Cornstarch and water form a polymer that sometimes acts like a liquid and sometimes acts like a solid.
When was it more like a liquid?
When was it more like a solid?
3. How are the two polymers you made today similar? How are they different?