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Lesson: Nano Waterproofing

keithlysm(Provided courtesy of TryNano.org) Level: Grades 6-12; Time required: Two to three 45-minute sessions.

ABOUT THIS LESSON:

This lesson focuses on how nanotechnology has impacted the design and engineering of many everyday items, from paint to fabrics. Students learn about the hydrophobic effect and how similar properties can be introduced by re-engineering products at the nano level. They then work in a team to develop a waterproofing plan for a piece of cotton fabric. Executing their plan, they test the fabric and examine samples of fabrics that have had their surface altered through nanotechnology.

Objectives

  • Learn about nanotechnology.
  • Learn about the hydrophobic effect.
  • Learn about surface area.
  • Learn about teamwork and working in groups.

HM3F1164.jpgAnticipated Learner Outcomes:

As a result of this activity, students should develop an understanding of:

    • Nanostructures • Surface Area • Problem Solving • Teamwork

CURRICULUM STANDARDS:

This lesson plans aligns to the National Science Education Standards and International Technology Education Association’s Standards for Technological Literacy as follows (please see Full lesson PDF for list of specific content standards):

National Science Education Content Standards, Grades K-4, 5-8, 9-12

  • A: Science as Inquiry
  • B: Physical Science
  • E: Science and Technology
  • F: Science in Personal and Social Perspectives

Standards for Technological Literacy, All ages

The Nature of Technology: Standard 1, 3

Design: Standard 9, 10

Abilities for a Technological World: Standard 11, 13

The Designed World: Standard 19

RESOURCES/MATERIALS:

  • Full lesson PDF (contains: Teacher Resource Documents, Student Worksheets, and Student Resource Sheets
  • NISE Net Website. Nanoscale Informal Science Education Network, a national community of researchers and  educators dedicated to fostering public awareness, engagement, and understanding of nanoscale science, engineering, and technology.
  • An introductory YouTube video on nanotechnology from Discoveryworks
  • Recommended Reading Nanomaterials, Nanotechnologies and Design: An Introduction for Engineers and Architects (ISBN: 0750681497) Understanding Nanotechnology (ISBN: 0446679569) Nano Materials: in Architecture, Interior Architecture and Design (ISBN: 3764379952)

THE LESSON:

Goal

This lesson focuses on how nanotechnology has impacted the design and engineering of many everyday items, from paint to fabrics. Students learn about the hydrophobic effect and how similar properties can be introduced by re-engineering products at the nano level. Students work in teams to develop a waterproof material and compare their results with nano waterproof materials developed recently by engineers and scientists.

Materials

  • Microscope or camera scope (optional activity)
  • Sink or bucket to test fabrics
  • One set of materials for each group of students:
    • Four 4″ x 4″ pieces of plain white cotton fabric
    • One 4″ x 4″ piece of fabric that has been adjusted at the nano level (Optional. Suggestion: purchase one white shirt made of nano fabric and cut up for distribution to the class. These can be purchased at many stores or online. A sample list is at www.nano-tex.com/company/brand_partners.html.)
    • “Waterproofing” materials: wax, crayons, flax seed, lanolin, clay, glue, or other items suggested by the students
    • Spoons or sticks for smoothing

Procedure

Introduction:

1. Teachers should decide the most effective ways to introduce a lesson of nanotechnology and the background information before beginning the specific activity on nanotechnology waterproofing. Please see our list of resources above, including the introductory video and additional nanotechnology lessons.

As part of the introduction, distribute to the Student reference sheets, which may be read in class or assigned for the prior night’s homework. If the reading is assigned ahead of time, students could be challenged to bring to class materials they predict could render a piece of cloth waterproof.

2. Set up a workspace that can accommodate the students’ experiment, including testing materials in buckets or a sink.

4. Divide students into groups of 2-3 students, providing a set of materials per group.

5. Explain to the students that they must devise a way to “waterproof” a piece of fabric that ultimately would be made into a shirt. In this case, “waterproof” means that water should not be absorbed by the fabric, but will bead up on the fabric instead. Students should select from, and experiment with, the waterproofing materials they have been supplied — wax, crayons, flax seed, lanolin, clay, and glue.

Planning Stage:

6. Students meet and develop a written plan for three different approaches: Fabric A, Fabric B, and Fabric C. The fourth fabric piece is provided in case of errors.

Manufacturing and Experimenting:

7. Students next “manufacture” their three fabric pieces, carrying out their plan.

8. In classrooms equipped with microscopes, students can examine their “waterproof” fabrics to see how the surface changed with each “waterproofing” system.

9. If possible, provide a sample of material altered at the nano-level for students to examine, as well. While students will not be able to see the changes using a regular classroom microscope, the lack of visible difference between unaltered cotton and nano-treated cotton will serve to demonstrate the power of different types of microscopes.

Testing Results, Drawing Conclusions

10. Student teams next test out their fabrics using buckets of water or a sink. Consider using colored water or fruit juice to test for staining. Students then complete the group evaluation/reflection worksheet. Afterwards, they should present their findings to the class and compare results.

Lesson Extensions

Model-making Extension: Have students build a model representing the Hydrophobic effect. This could be done with a foam ball with straws or toothpicks attached to simulate the tiny hairlike projections that keep water off the direct surface of some leaves. This will also help visually illustrate how waterproofing works at the nano scale.

Writing Activity: Have students write an essay or a paragraph about potential benefits of applying nanotechnology to fabrics, surfaces, or materials used in hospitals or nursing homes.

Reversal Activity: Have older students attempt to remove the waterproofing feature of nano fabrics in any way they can think of. For example, they might scrub the surface, dye it, boil it, wash it, freeze it, or iron it.

—————————————————————————————————

Text from the STUDENT SHEETS (See PDF Version, with illustrations and charts: Student Sheets)

Student Sheet #1. What is Nanotechnology?

Imagine being able to observe the motion of a red blood cell as it moves through your vein. What would it be like to observe the sodium and chlorine atoms as they get close enough to actually transfer electrons and form a salt crystal or observe the vibration of molecules as the temperature rises in a pan of water? Because of tools or ‘scopes’ that have been developed and improved over the last few decades we can observe situations like many of the examples at the start of this paragraph.

This ability to observe, measure and even manipulate materials at the molecular or atomic scale is called nanotechnology or nanoscience. If we have a nano “something” we have one billionth of that something. Scientists and engineers apply the nano prefix to many “somethings” including meters (length), seconds (time), liters (volume) and grams (mass) to represent what is understandably a very small quantity.

Most often nano is applied to the length scale and we measure and talk about nanometers (nm). Individual atoms are smaller than 1 nm in diameter, with it taking about 10 hydrogen atoms in a row to create a line 1 nm in length. Other atoms are larger than hydrogen but still have diameters less than a nanometer. A typical virus is about 100 nm in diameter and a bacterium is about 1000 nm head to tail. The tools or new “scopes” that have allowed us to observe the previously invisible world of the nanoscale are the Atomic Force Microscope and the Scanning Electron Microscope.

Scanning Electron Microscope The scanning electron microscope is a special type of electron microscope that creates images of a sample surface by scanning it with a high-energy beam of electrons in a raster scan pattern. In a raster scan, an image is cut up into a sequence of (usually horizontal) strips known as “scan lines.” The electrons interact with the atoms that make up the sample and produce signals that provide data about the surface’s shape, composition, and even whether it can conduct electricity.

Student Sheet #2

What is The Hydrophobic Effect? Hydrophobic comes from the word hydro (water) and phobos (fear). It can be demonstrated by trying to mix oil and water. And, also is evident if you look at some leaves and flower petals that repel water in droplets after a rain storm. For the leaves, the water repellant can sometimes be a waxy coating on the leaves, or can be the existance of tiny hairlike projections off the surface of the leaf which causes a buffer of air between the hairs — the air keeps the water away.

1281364_lotusSuperhydrophobic Surfaces Superhydrophobic surfaces such as the leaves of the lotus plant have surfaces that are highly hydrophobic, or very difficult to wet. The contact angles of a water droplet exceeds 150¡ and the roll-off angle is less than 10¡. This is referred to as the Lotus effect and the image to the right illustrates this concept.

Fabric Applications? Scientists and engineers who were aware of the hydrophobic effect decided to apply nanotechnology to the surfaces of fabrics to make them water proof too. The waterproof feature often also helps protect fabrics from staining because liquid cannot easily soak into the fabric fibers. A good example is the work done by a company called Nano-Tex. The company adds nano “whiskers” to cotton fibers in the same way that some leaves have little “hairs” on their surface. Creating the effect for fabric is a little tricky — a cotton fiber is shaped like a round cylinder, and NanoTex adds tiny nano “whiskers” all around the cylinder so it has a fuzzy surface. The fabric doesn’t appear any different or feel any different, but it does repel liquids. And, because liquids do not soak into the fabric, the process also helps the fabric resist staining too.

Nano-Tex utilizes nanotechnology to: 1.) design molecules with specific performance attributes; 2.) engineer the molecules to assemble on the surface of textile fibers with extreme precision, and 3.) ensure that they permanently attach to the fibers through patented binding technology. If the molecules were not permanently attached then the fabric might lose its ability to push water away after several machine washings. Over 80 textile mills worldwide are using Nano-Tex treatments in products sold by more than 100 apparel and commercial interior brands. This is just one example of an industry applying nanotechnology to solve problems–explore more examples at www.trynano.org.

Student Sheet #3. Student Activity: Waterproofing Challenge

You are part of a team of engineers who have been given the challenge to develop a new process for waterproofing clothing. You have been provided with several pieces of cotton along with many possible materials you might decide to use for your waterproofing technique. For the purposes of your challenge, “waterproof” means that water should not be absorbed by the fabric, but will bead up on the fabric instead. You may try two or three different solutions and see which works best.

Planning Stage: Meet as a team and discuss the problem you need to solve. Use the Student Sheets to describe your solution and list the materials you think you’ll need to meet the challenge. Explain why you think your solution will solve the problem! Manufacturing Stage Execute each of your plans (be sure to mark each piece of fabric, so you know what process you applied to it).

Investigation Stage: If you have access to a microscope, examine each of your pieces of fabric and in the box on the student sheet, describe what you see, noting both what you see and how they differ from the other fabric samples. You’ll have a chance to examine a sample of fabric that has been altered at the nano level too! Consider whether the fabric surfaces appear smooth, bumpy, convex, concave, or have other characteristics.

Testing Stage: Over a wash basin or sink pour water over your fabric and see if it beads up or is absorbed. If your teacher agrees, you may wish to use a colored water or juice to more easily see if the water is absorbed at all. Mark your observations on the student sheets.

Evaluation Phase.

Complete the following questions as a group:

1. Did any of your fabrics prove to be waterproof? If yes, which procedure do you think was the best, and why? If no, why do you think your procedures did not work?

2. What solution of another team do you think worked best? Why?

3. What do you think would happen if you washed and dried your fabric? Would it retain the waterproofing?

4. What was the most surprising observation during the microscope comparison (if you completed that part of the activity)?

5. How did the nano treated fabric compare to your most successful fabric in the water test?

6. How did the nano treated fabric compare to your most successful fabric under the microscope?

7. If you had to do it all over again, how would your team have approached this challenge differently? Why?

8. Do you think that materials engineers have to adapt their original ideas during product testing? Why might they?

9. Did you find that there were many different solutions in your classroom that met the project goal? What does this tell you about how engineering teams solve problems in the real world?

10. Do you think you would have been able to complete this project easier if you were working alone? Explain.

11. What other applications can you think of where a surface might be changed at the nano scale to improve function or performance? One idea is coating windshields so water flows off faster…..what can you think of?

Developed by IEEE as part of TryEngineering: www.tryengineering.org

http://www.physicscentral.org/experiment/physicsquest/index.cfm

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