Download Organic Chemistry: Polymerization Reactions

Organic Chemistry:
Polymerization Reactions
Today’s Objectives:
1) Define, illustrate, and give examples of monomers, polymers, and
polymerization in living and non-living systems
STS: 2) Illustrate how science and technology are developed to meet societal
needs and expand human capabilities
STS: 3) Illustrate how science and technology have both intended and
unintended consequences
Section 10.5 (pg. 445-459)
Polymerization

Polymers are large molecules made of
chains of monomers, small molecules that
link together.
 Polymerization is the formation of
polymers from these small units

Polymers can occur naturally (proteins,
carbohydrates) and can be
synthesized (nylon, Teflon, polyethylene)

They play an integral part in the
function of life systems and have
revolutionized the way society functions
Addition Polymerization


Many plastics (synthetic polymers) are made by this process
The polymerization process is initiated with a free radical (a species
with an unpaired electron). The free radical attacks and breaks the
double bond forming a new free radical that attacks another monomer



Addition Polymerization always results in one product, the polymer
Requires unsaturated hydrocarbon monomers and bond saturation
occurs when the polymer is made
Common polymers produced by addition polymerization:
Things to know about addition polymers…

The polymer names end in –ene (i.e. polystyrene, polypropene). Does this
mean they have double bonds?
 No, the double bonds are saturated by adjacent monomers, as the
polymer is made. The name refers to the starting monomer (i.e.
polyethene is started by the monomer ethene)

What properties make Teflon a good product for non-stick materials?
 Teflon is made up of C-F bonds which are very strong (not C-H bonds).
These very strong bonds make the Teflon highly unreactive (non-sticking),
it has a high melting point and it has a slippery surface
Condensation Polymerization


Monomers combine to form a polymer and a bi-product. Each
time a bond forms between monomers, small molecules, such as
water, ammonia, or HCl are “condensed” out.
The polymerization of nylon:
• For condensation polymerization
to occur, monomers must be
bifunctional, meaning they have
at least two functional groups.
• If they only had one functional
group, then only one bond would
form.
Condensation Polymerization


Condensation polymerization also produces natural polymers,
called proteins.
Amino acids (monomers) polymerize to make peptides (short
chains of amino acids) or proteins (long chains of amino acids)
Comparison of Addition and
Condensation Polymerization
Addition


Needs a double or
triple bond in the
monomer
Produces only one
product, the polymer
Condensation


Needs bifunctional
monomers (have two
functional groups)
Produces two products:
the polymer and the
biproduct (water,
ammonia or HCl)
Polyester


When a carboxylic acid reacts with an alcohol in an esterification
reaction, a water molecule is eliminated and a single ester molecule
is formed.
This esterification reaction can be repeated so many esters are
joined in a long chain… a polyester


This is created using a dicarboxylic acid (an acid with a carboxyl group
at each end) and a diol (an alcohol with a hydroxyl group at each end)
The ester linkages are formed end to end between alternating acid and
alcohol molecules
Polyester: Dacron

Another example of a polyester:

Note the two carboxyl groups in the dicarboxylic acid and
the two hydroxyl groups in the polyalcohol that start the
chain reaction
Natural Polymer Examples

Starch, wood, silk, DNA
Today’s homework



Pg. 448 #2-4
Pg. 452 #13
Pg. 455 #16, 17


Due tomorrow
What is coming up tomorrow?
 Review
for Unit Exam
Learning Tip Pg. 441
Unit Exam
Chemistry 30 Organic Review