Nanocomposites

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Nanocomposites

• Ann M. Comins
• UW-Madison MRSEC
• Research Experience for Teachers
• Summer 2006

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What is a Composite?

• Two or more materials combined to form a single
  component
• Matrix surrounds and supports filler, absorbs
  energy when under stress
• Filler imparts certain property, often adding
  strength and reducing weight of the matrix

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What is a nanocomposite?

• Material made by adding nanoparticles into a
  macroscopic sample
• Carbon nanotubes
• Clay-based
• Change electrical and thermal conductivity and
  enhance mechanical strength
• Generally added during processing
• 0.5-5 nanomaterials by weight

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Types of Nanocomposites

• Natural
• Bone material-collagen fibrils reinforced with
  nano-sized mineral particles
• Man-made
• Sports equipment

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Project Goal/Curriculum Connections

• Integrate nanocomposites into the standard
  chemistry curriculum
• Heterogeneous mixtures
• Redox chemistry
• Electrochemistry
• Materials chemistry
• Magnetism

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Activity Goal

• Practice Lab Techniques
• Understand/explain what a nanocomposite is and
  how it relates to standard chemistry curriculum
• Design an experiment
• Collect, compare, and analyze data
• Make conclusions/modifications

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Nickel Nanowires Plaster

• Create nanocomposite by making Ni nanowires and
  adding them to plaster
• Relatively cheap
• Procedure for high school relatively easy and
  complete
• More real to the students-make own nanoparticle
  and place into plaster
• Easy to test the strength and compare

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Student Lab/Activity

• Make Ni nanowires-use in nanocomposite, not just
  fun magnetic
• Inquiry lab
• Plain plaster piece
• Other plaster piece-sand, gravel, etc.
• Ni nanowires plaster
• Test properties, namely strength

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More Specifics

• Target grade level high school and undergraduate
  college classes
• Time investment
• 50 min class period to make nanowires
• Longer if you want to get longer wires
• 50 min class period to make various plasters
• 50 min class period to test pieces
• Class time to discuss nanocomposites, results,
  and connections to other topics

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Ready, Set, Go!
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Making Ni Nanowires

• Using the current MRSEC lab, students make Ni
  nanowires

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More Steps to the Experiment
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Final Experiment Steps
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Nickel Nanowires

• Plated Ni for various amounts of time-different
  lengths of wire
• Transfer Ni nanowire solution to plaster with
  magnet
• Make nanocomposite

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Ni Nanowire/Plaster Test

• Test piece in weigh boat
• Use 2 freezer bags in hood
• Test with magnet next day
• Assumed safe

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Molds for Plaster Pieces

• Make
• Poster board with cling wrap
• Juice container
• Time issue
• Buy
• Plastic mold
• Straws
• Money issue

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Plaster Problems

• How to fill straws
• syringe
• How to add Ni nanowires to plaster
• Use magnet
• Safety
• Solution in vial to liquid plaster
• How to get plaster piece out of straw

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Ni Nanowire/Plaster Steps
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More Steps to Experiment
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Ready to Test

• 3 pt. test - apparatus/hang weights in middle and
  see when it breaks
• Cut plaster straw into 3 pieces
• Break plaster in straw
• Can not see when plaster breaks
• Cut straw away
• Plaster actually not dry after 1 week

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New Straw Molds

• Cut the straws in half so that the plaster can
  harden in one day
• Crease straw and use scissors to cut straw in
  half-obtain 2 molds
• Smooth plaster with spatula to get an even layer

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Straw Modifications
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Safety
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Safety Problems ?

• When the plaster breaks will Ni nanowires become
  airborne
• Are there enough particles to matter?
• Is there a way to contain Ni nanowires in
  plaster?
• Use hood/freezer bags/contact paper
• Absence of studies on hazards of Ni nanowires due
  to inhalation

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More Safety Thoughts

• Limited exposure for students
• More of a problem for teachers-repeated exposure,
  Ni preparation (toxic/carcinogenic)
• Particles only nano in one direction
• Low concentration of Ni nanowires in plaster
• See black specks in plaster-not nano then?

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Possible Ways to Determine if Nanowires Stuck in
Plaster

• Slice a section
• Look at it under an optical microscope
• SEM
• X-ray diffraction
• Should we do this, if not sure of safety?

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Future Work

• Continue to test for safety
• If deemed safe
• Test strength of nanocomposite
• Figure out the amount of nanowires in plaster
  necessary to observe a difference in strength
• Create lab where students test whether or not
  amount of nanowires in plaster affects its
  strength

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Alternate Educational Activities

• Discuss lab safety and research
• Risk and benefit analysis
• Compare nanocomposites that are already
  manufactured
• Golf balls
• Bumpers from certain vehicles
• Tennis rackets
• Baseball/softball bats

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Content Standards

• Science Connections
• Nature of Science
• Science Inquiry
• Physical Science
• Science Applications
• Science in Personal and Social Perspectives

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Acknowledgements
George Lisensky
Wendy Crone
Mike Condren
Greta Zenner
University of Wisconsin-Madison
Cindy Carter
Dana Horoszewski
Ken Gentry
Jen Ehrlich
Tony Cina
Farrell Rogers
John Whitsett
Sue Whitsett