Akron Global Polymer Academy Lesson Plans

The Engineering Design Process: Aerogels

Grades: 6-12
Author: Marjorie Langston
Source: The lesson is the original work of the author. This material is based upon work supported by the National Science Foundation under Grant No. EFC-1542358

Abstract

Research currently being done at the University of Akron involves the creation of a gel polymer emulsion to make aerogels. The emulsifying agent (and dissolved phase) in the gel cannot simply be evaporated out because the holes left behind in the gel will collapse. Thus, a multistep solution exchange process is performed to get rid of the emulsifying agent (and dissolved phase) and leave the pores (holes) left behind intact. The result is a solid with lots and lots of holes in it called an aerogel.

Aerogels have been used in recent years by NASA and other entities because they have unique properties like being of a very low density and being incredible thermal insulators. Though they are very useful, aerogels are not widely used because it is still expensive to manufacture them on a large scale.

In this lesson, students will mimic polymer/process engineers by designing a process to eliminate chocolate chips from chocolate chip cookie dough (their "gel") without destroying the holes left behind. This is a STEM lesson is in which the engineering design process is taught. An engineering design notebook is provided as well as metrics (including required teacher signatures at various points and Self, Peer, Group Evaluations) for ensuring that all students are on task at all times. Further, this notebook makes assessing individual contributions to the cooperative assignments easier many other projects.

Objectives

What should students know as a result of this lesson?

• Scientific Inquiry
• STEAM/21 st Century Skills-collaboration, communication, creativity, critical thinking, conflict resolution, perseverance
• The engineering design process
• The following terms: emulsion, emulsifying agent, compressive strength, aerogel, immiscible
• Macrostructure of aerogels; properties and uses of aerogels; how structure influences properties and thus uses of a material
• That aerogels are important substances being researched at the University of Akron and NASA

What should the students be able to do as a result of this lesson?

• Explain/Define: the engineering design process, emulsion, emulsifying agent, compressive strength, aerogel, issues with making aerogels
• Use the engineering design process and STEAM/21 st Century Skills (collaboration, communication, creativity, critical thinking, conflict resolution, perseverance) to design a process
• List properties of aerogels
• Explain how structure affects properties which affects uses of a material

Materials

• Aerogel Sample ($30-$100)-can be purchased from http://www.buyaerogel.com/ or http://aerogeles.com/ . These samples are important. Alternatively, you could contact the manufacturer as ask them to donate samples to your class. Also, you can contact the Akron Global Polymer Academy to see if the research labs have samples they plan to throw away.
• 4-8 packages premade chocolate chip cookie dough (or supplies to make it) for a class of 24 working in pairs (2-4 samples each round per pair) ($8-$20)
• Basic lab supplies; basic household items like milk, oil, vinegar; cleaning solutions
• Access to a heat source (Bunsen burner, oven/toaster oven) is helpful
• Access to the internet and computers/tablets/smartphones/etc.; Google Slides, PowerPoint, or other presentation software
• Supplies for liquid nitrogen demo or dry ice demo:
  • Liquid Nitrogen: liquid nitrogen; liquid nitrogen gloves; items such as live flowers, a racquetball and hammer, a balloon, grapes, scallions, etc. for a demo. A large cutting board (or work surface) and a bucket or deep ceramic baking dish, can be purchased from thrift stores, etc., may be helpful.
  • Dry Ice: dry ice, containers, indicator, bottle, tubing, cup with lid, etc. (See videos.)
  • Note: Your local university or a private company may have science outreach programs that bring liquid nitrogen to schools. Some even do the demos for you.
• Candy mixture to use to determine pairs/groups

Procedures

A weeks prior:

• Order aerogel samples from http://www.buyaerogel.com/ or http://aerogeles.com/

Engagement

• Ask your administration for a permission slip that will allow you use pictures of students working and their work samples for edu
• Mention the engineering design challenge to students.
  • Design a means for removing chocolate chips from chocolate chip cookie dough and leave the holes left behind intact.
• Tell students to be thinking of ideas and gathering supplies. Notify them that they will have a say in the design constraints (what substances are they allowed to use/not allowed to use, if cost will be a factor, etc.). Also, notify them that you will be choosing groups.
• View and plan your liquid nitrogen demo or dry ice demo. There are lots of videos on the internet that you can use for ideas. Here are a couple:
  • Liquid Nitrogen:
    • https://www.youtube.com/watch?v=0kMqRhJ_A0c
    • https://www.youtube.com/watch?v=enEtTV-FyCU
  • Dry Ice:
    • https://www.youtube.com/watch?v=dXq0ao2GmrQ
    • https://www.youtube.com/watch?v=72fYfqZCwaY

Note: USE ETREME CAUTION WITH LIQUID NITROGEN AND DRY ICE

Handouts for almost assignments except the Pre and Post test are in the Engineering Design Notebook.

Day 1-2:

• Liquid nitrogen demo or dry ice demo.
• Intro: Aerogel Teacher Demo-Have a volunteer hold their eyes closed and hands out. Put an index card in each hand and then an aerogel sample on one hand. Have student guess which hand. To minimize concern, tell the class what you will do before you choose a volunteer. You can let the students do this to each other. My students enjoyed trying to fool each other!
• Pre Test
• Mention design challenge again.

Exploration

Day 3:

• Each day moving forward, have students watch 1-2 videos from the video list found at the end of this lesson and start recording answers in the Basic Info Section (the first page) of their Engineering Design Notebook.
  • Note: Students must watch all videos to get all answers and some answers (i.e. uses, properties, etc.) are in more than one video.
  • Second Note: One video references liquid nitrogen and another references dry ice so that is why those demos are included in this unit.
• Post the entire video list in the Google Classroom, Drive, your teacher website, etc.
• Introduce/review problem and engineering design challenge by reading the paragraphs below which is also in their Engineering Design Notebook:
  • The Situation
    
    When you shake a bottle of oil and vinegar salad dressing and look at it (before the layers separate), you are looking at an emulsion. An emulsion is a heterogeneous mixture of two immiscible substances dispersed in each other. Often an emulsifying agent is added to prevent the layers from separating.
    
    Aerogel research is currently being done at the University of Akron to create coatings for clothing/masks which can filter out contaminants and thus improve our health. It is also being done create better matrices for cells to grow on to fight disease, aid injuries, etc.
    
    This research involves the creation of an aerogel by first creating a gel polymer emulsion. Unfortunately, the emulsifying agent and dissolved liquid cannot simply be evaporated because the holes left behind in the gel will collapse. Thus, multistep solution exchange process is performed to get rid of them and leave the holes left behind intact. This involves the sample being soaked in a solution for 24 hours, put into a (different) solution for 24 hours, and then a third liquid for 24 hours before the sample is soaked and dried with supercritical liquid carbon dioxide. The result is a solid with lots and lots of pores (holes) in it called an aerogel.
    
    Due to their unique structure, aerogels have many properties that make them very useful. However, aerogels are not widely used because it is still expensive to make them.
    
    Today, you are a polymer engineer. Your job is to start with a mixture and come up with a means of eliminating part of the mixture without destroying the holes left behind. Your sample "gel" is chocolate chip cookie dough.
• Have class come up with design constraints (what materials are allowed, how much of a material is allowed, what lab equipment is allowed, etc.). Note: You may want to have students not be able to remove the chips manually and to require that the cookie dough be in its original shape at the end. Ironically, removing
• Have students complete the first box of the Imagine/Brainstorm Page of the Engineering Design Notebook. Remind students that they will be able move on once every person has an idea written on their paper.
• Handout a candy mixture. Students with the same candy type are paired with each other. Pairs are preferred. Groups should not be larger than 3.
• Allow students to chat with their partner, come up with team names, and complete the rest of the Imagine/Brainstorm page of the Engineering Design Notebook. Sign the pages. Note: Signing is a means of making sure each person/group is on task and progressing. Also, it allows you to quickly check work/provide feedback and input points later.
• Have students complete Project Planning Log. Sign the logs.