Students examine viscoelastic, mechanical, and absorptive properties of polymers. They design and test a nonelectrical humidity sensor made of a polymer film.

By incorporating everyday materials into science lessons, the Materials World Modules (MWM) program at Northwestern University has found the solution to getting students excited about learning science while helping teachers meet national and state education standards.

The modules are easy to organize and inexpensive to run. They can be incorporated into any science class because of the breadth of subjects covered in the Activity and Design Project sections. Each module is a supplemental science unit that takes 1-3 weeks of class time (approximately 10 hours) to complete.

MWM will give students an opportunity to understand the world around them in a way they have never experienced before. The modules promote an awareness of the roles science and technology play in society and guide students to take increased control of their work.

» Module At-a-Glance
» Connecting to Your Curriculum
» Video Clips
» Resources

Activity 1: Changing Polymer Pellets
Students compare the absorptive properties of polymer pellets in plain water and in a saturated salt solution. Based on their data, students draw conclusions about the application of this polymer in gardening and other areas.

Activity 2: Hunting for Polymer Products
Students conduct a hunt in their home or school to identify objects made of polymers. Students classify, describe and, if possible, also identify the particular polymers the products are made of.

Activity 3: Comparing the Viscosity of Liquids
In Part A, students compare the viscosity of methanol, ethylene glycol, and glycerol and then draw conclusions about why most polymers used in daily life are solid. In Part B, students spread, or cast, different solutions of poly (vinyl acetate) onto glass slides to observe the effect of polymer molecular weight and concentration on the viscosity of the solutions. Students also gain experience casting polymer films.

Activity 4: Testing the Strength of Different Polymer Films
In Part A, students cast poly(vinyl acetate) films that differ in molecular weight and then test the films' hardness and stretchability by hand. In Part B, students compare the tensile strength of the films by hanging a weight from each film and measuring changes in film length over time. Based on their data, students draw conclusions about the effect of polymer molecular weight on the hardness, stretchability, and tensile strength of polymer films.

Activity 5: Measuring Water Absorption by Different Polymer Films
Students cast films of polystyrene, poly(vinyl alcohol), and three molecular weights of poly(vinyl acetate) and then test water absorption by each film. Students learn about the effects of monomer type and film thickness on water absorption by polymer films.

Design Project 1: Designing a Humidity Sensor
Students construct prototypes of a humidity sensor in the form of polymer films embedded with cobalt(II) chloride, which changes color as the surrounding humidity changes. Students test and evaluate their prototypes and redesign them to make them more effective.

Design Project 2: Designing a New Polymer Product
Students use polymers to design a new product or improve an existing one. Students construct, test, evaluate, and redesign prototypes of their product to determine the best design for that product.

[ Back to top ]

Materials World Modules are simple to organize and inexpensive to run. They are designed to be easily incorporated into any middle school science or high school science lab or lecture course. The chart below lists the subjects covered in the Activities and Design Projects sections of this module.

[ Back to top ]

MWM's Polymer Simulation
Provides an introduction, including computer simulations, to two general types of polymer synthesis, or polymerization: (1) condensation or step-growth polymerization and (2) addition or chain-growth polymerization.

[ Back to top ]