Transcript Polymerization Reactions - SCH4U1-CCVI

Polymers are large molecules made by
linking together many smaller molecules,
called monomers.
monomers
monomer
symbol
polymer
n
Natural polymers include proteins, lipids and
carbohydrates.
Synthetic polymers include plastics, nylon, acetate, and polyesters.
Polymerization reactions can either be classified as addition
reactions or as condensation reactions.
Synthetic Addition Polymers
Addition polymerization is a reaction where monomer units join
each other in a process that involves the rearranging of electrons in
double or triple bonds in the monomer.
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Polyethylene: A Polymer of Ethene (Vinyl)
Ethene has 2 pairs of shared ein the double bond.
High temperature or UV light can cause 2
of these shared (paired) electrons to become
unshared (unpaired).
Polyethene (Polyethylene or Vinyl)
Here’s another way to see the chain reaction.
These are the carbon atoms with their doublebond (2 shared electrons each). The hydrogen
atoms are not shown. A collision breaks the
first bond.
Once the first double bond is broken, a chain reaction will occur.
In about a second an entire chamber of compressed ethylene gas
turns into the polymer, polyethylene.
When the chains
get up to 500,000
carbons long, they
are tough enough
for synthetic ice,
replacement joints,
and bullet-proof
vests.
This is called high
density polyethylene
(HDPE). See p. 139
in textbook
Low density polyethylene
(LDPE) is made by
causing the long chains of
ethylene to branch.
That way they cannot lie next each other, which reduces the
density and strength of the polyethylene. This makes the plastic
lighter and more flexible.
Low density polyethylene is used to make things like plastic bags,
plastic wrap, and squeeze bottles.
Polypropene
It is more commonly called polypropylene.
Polypropylene is used to make things like
carpet, rope and thermal underwear.
Polyvinyl Chloride
PVC is one of the most widely used polymers, with
dozens of practical applications.
PolyVinyl Chloride (or PVC) is almost the same as
polyethylene, except every second hydrogen is replaced
with a chlorine atom (green sphere).
Polyvinyl Chloride (PVC)
raincoats
upholstery
siding
wire insulation
pipes and fittings
Polyvinyl Alcohol
• Uses include – white glue, post it notes,
“silly puddy”, “slime” etc…..
Polystyrene
When a benzene ring is attached to an ethene
molecule, it is commonly called styrene.
Polystyrene
trays
cups
coolers
packing materials
Teflon
Teflon® is the product name for the polymer used
to make nonstick cookware.
It is composed of a series of tetrafluoroethene
monomers.
Recently, concern has been growing
regarding the possibility that Teflon®
releases toxic chemicals if it gets too hot.
Important
constitutions
for synthetic
polymers
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Crosslinking
• By using another atom – C group or OH or S the polymer
can be strengthed and also control of the structure can
be forced
Polyesters
Polymers from Carboxylic Acids and Alcohols
A polyester is a series of ester molecules joined in a long chain.
dicarboxylic acid + polyalcohol → polyester + water
The dicarboxylic acid has a carboxyl group at each end of the molecule
and the polyalcohol (a diol) has a hydroxy group at each end.
Notice two carboxyl
groups at the ends of
each carboxylic acid.
Notice two hydroxyl
groups at the ends of
each alcohol.
Nylon
Polymers from Carboxylic Acids and Amines
A polyamide is a long chain caused by the repeated bonding og
dioic acids and diamines.
Nylon was synthesized as a substitute for silk, a natural polyamide.
The Hydrogen bonding cross linking of the Nylon gives it it’s strength.
Kevlar
The polymer chains form a
strong network of hydrogen
bonds that hold adjacent chains
together in a sheet-like structure.
Formation of a polyamide
O
HO
O
O
OH
NH2
OH
HO
NH2
Formation of a polyamide
O
HO
O
O
NH + H2O
HO O
H2N
NH2
OH
NH2
OH
Formation of a polyamide
O
O
O
HO
NH + H2O
HO O
H2N
NH
O
NH2
OH
NH2
OH
+ H2O
Formation of a polyamide
O
O
O
HO
NH + H2O
HO O
H2N
NH
O
NH
NH2
OH
+ H2O
+ H2 O
Formation of a polyamide
O
O
O
HO
NH
HO O
H2N
OH
NH
O
NH
NH2
A polyamide “backbone” forms with R groups
coming off. This protein is built with amino acids.