Transcript What is a Polymer?

What is a Polymer?
Withrow University High School
May 2008
Definition
The word polymer comes from the Greek language.
poly - mer
many - parts
So, polymer means
“many parts”.
A Polymer Molecule
• A polymer is a Giant Molecule.
• This giant molecule is a long chain of identical
repeating units.
• These repeating units are called monomers.
• A polymer molecule are made up of 1000s of
monomers.
M
M
M
M
M
M
M
M
Natural Polymers
Cotton from plants is a
natural polymer and is
used to make clothing
Silk from silk worms is
used to make cloth
Wood is a natural
polymer used for paper
Natural latex from
rubber tree is a polymer
Rubber can be used
to make tires
or rubber bands!
Crustacean shells are
made of chitin, a
natural polymer
“Carbs” like spaghetti
are natural polymers
Proteins from eggs and
other foods are also
natural polymers
Man-Made (Synthetic) Polymers
Polyethylene is used to
make plastic sandwich bags
Milk jugs are made from the
synthetic polymer
polyethylene (HDPE)
Synthetic polymers are used
to make specialty athletic
clothing using polymer such
as Polyester, Nylon, Lycra or
spandex
Compact Discs are made
from synthetic polymers
such as polycarbonate
Soda bottles are made from
polyethylene terephthalate
(PETE)
Polystyrene is used to make
Styrofoam cups and cd cases
Can you think of any
other types of man
made polymers and
their uses?
Symbol
• The pictures below represent a polymer chain.
M
M
M
M
M
M
M
M
M
M
M
M
M
• The “M” stands for monomer.
M
M
M
Elasticity makes the ball bouncy.
• An elastic object is able to change shape and
return to its original shape.
1. The
ball drops
2. The ball
changes shape
when it hits the
floor.
3a. The ball
returns to its
original
shape.
3b. The ball
pushes off
the ground
4. The ball
bounces
back up.
Floor
• What’s going on inside?
• The molecules stretch when a force is applied.
• When the force is removed, the molecules return to
their original shape.
Polymers make the best elastics
A polymer
chain at rest
M
M
M
M
M
M
M
M
A force pulls and
stretches the
polymer chain.
A force pulls and
stretches the polymer
chain
M
M
M
When the force is
removed, the
polymer chain goes
back to its original
shape, as long as it
was not stretched
too much! That
would cause the
bonds to break.
M
M
M
M
M
M
M
M
M
M
M
M
M
Example Monomer
• Mono = “One” Put it together with mer to get?
– One part
• Tiny molecular unit that can chemically
combine by covalent bonds with other
monomers to form a long chain called a
Polymer
H
H
Ethylene monomer
molecule (C2H4)
C=C
H
H
Polymer Synthesis
• Monomers combine chemically through
covalent bonds to form long chain polymer
molecules.
• For Polyethylene the double bond between
the carbons is ‘opened’ up and attached to
another carbon atom of an ethylene monomer
and the process continues as the molecule
grows in size.
How to Represent Polymers
• Polyethylene (PE)
– Plastic bags, milk jugs,
sockets for hip joint
replacements, etc.
• Polyvinyl chloride (PVC)
– Piping, house siding, turntable
records, etc.
• Polyvinyl Acetate (PVA)
– Glue, binder for making
sheets of paper, binder for
paints
H
H
[ C ĞC ]
H
H
n
H
Cl
[ C ĞC ]
H
H
H
H
[ C ĞC ]
H
n
n
O
COCH3