Human Polymers
Introduction & Motivation
To begin teaching students about how chemical engineers use polymers as a material, they must first understand what polymers are. The goal is to introduce it in a casual, fun, and basic way that is intuitive and relates to real-life. This activity will help students learn the basics of polymers, how they are formed, and their characteristics.
Polymers are large molecules (macromolecules) formed of many repeated subunits (monomers). There can be thousands or even millions of monomers forming a polymer. These monomers are composed of carbon with other elements such as hydrogen, oxygen, nitrogen, sulfur, chlorine, and fluorine attached to the carbon atoms. Depending on which elements are attached, their order, and their structure, the properties of the polymers vary widely. Some are stretchy, some very strong and tough, and others can be anywhere in between.
Some polymers are linear, meaning that you can trace the polymer from beginning to end in one line. However, these linear polymers do not have to be straight. They can be flexible, coiled up and curvy. Other polymers are branched just like a tree. Sometimes, polymers can be made stronger by adding what are called cross-links which are like bridges between a polymer and other polymers. These structural variations, as well as the monomers that constitute the polymers and their functional groups, affect the properties of the polymer. By changing the monomers and how they are attached to each other, you can change the properties of the polymer and get a new material!
There are tons of polymers found in nature, such as natural rubber and DNA. Other polymers are manufactured, such as Styrofoam, plastic utensils, tires, phone cases, etc. You touch a polymer every day!
This activity is incorporated into the Atoms, Molecules, and Polymers, Oh My! activity. In the middle of the presentation, there is a break for students to experience some qualities of polymers through this fun game.
Materials
- Chairs and open space!
Procedure
Arrange chairs in a maze-like configuration in the classroom.
- Have groups of students form a line by holding hands. Each of them will act as a monomer, and by joining hands will form a polymer. Reinforce that each of the students is different and has their own personality and properties just like the monomers have their own properties. Ask the students to try to navigate their way through the maze of desks and chairs, noticing how long it takes for their chain to completely pass a desk. Debrief before continuing.
- Have the students split up into several smaller chains and perform the activity again for a few minutes. Debrief before continuing.
- This time have students form two polymer chains, with one or two students acting as “cross-links” between the chains holding them together. Ask the students to make their way through the maze again.
Discussion
- What kind of properties do the chains of students have in common with polymers? (Students should be able to say that they are flexible and can wind around the obstacles. They can also stretch and compress and change their shape very easily.)
- Once the activity is performed with smaller chains, what do the students notice about their movement? (The smaller chains of students should be able to move more quickly and easily around obstacles, similarly to how short polymers are more fluid and can flow more quickly and freely.)
- When a few students acted as cross-links, was it easier or harder to move through the maze?