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Polymers (a.k.a. coffee cups, DNA and slime!)
Polymers are long-chain molecules made up of many small subunits called
monomers. The monomers may or may not all be identical. Polymers are very
important in the natural world as well as in modern chemistry. Examples of
common polymers are polyethylene, polyester, Teflon, proteins and DNA.
Synthetic Addition Polymers
 form by addition reactions of monomers with C=C bonds
 similar to addition reactions of alkenes studied earlier this unit:
Addition of bromine to ethene:
H
+
C C
H
H H
H
Br
Br
H C C H
Br Br
H
Addition of ethene to ethene (to ethene…thousands may join!):
This polymer (polyethene) can be written in condensed form:
 some other addition polymers:
 polyvinylchloride (PVC)
 polystyrene (coffee cups)
 polytetrafluoroethene (Teflon)
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Properties of polymers
 unreactive (since carbon-carbon bonds are saturated)
 flexible/mouldable; increases with heat (only London forces present - maybe
dipole-dipole if other functional groups present)
 strength of polymers can be increased with crosslinking (forming bonds
between polymer chains); usually requires “dienes;” properties depend on %
diene present when polymer is made
eg. neoprene (used in wetsuits)
eg. with an inorganic crosslinker: vulcanization of rubber
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Synthetic Condensation Polymers
 form when monomers join through ester or amide linkages via “dehydration
synthesis” reactions
ester synthesis:
think back to the lab… carboxylic acid + alcohol  ester
polyester synthesis:
polyamide synthesis:
Kevlar:
Homework:
pg. 102 #1,2
pg. 107 #4,5(top)1,2,6,7(bottom)
pg. 111 #2,3
pg. 113 #1
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Natural Polymers (Biopolymers)
A) Proteins (polyamides/polypeptides)
 monomers: (L-)amino acids (20 different common amino acids exist) whose
‘R’-groups determine the properties of the polypeptide chain
pg. 119: Amino acids in groups based on polarity
 linkage: an amide bond, commonly called a peptide bond or peptide linkage
formed by the reaction between the carboxylic acid and amine ends of the
monomers (dehydration synthesis)
 the order of amino acids in the polymer will determine the final shape (and
therefore function) of a protein
*** glance at pg. 122.
Structure is…
primary = 1° ____________
secondary = 2° ______________
tertiary = 3° ______________
quaternary = 4° _______________
B) Carbohydrates (polysaccharides)
 monomers: sugars (most commonly glucose but also fructose, galactose,
etc.)
 linkage: an ether linkage formed by the dehydration synthesis of two sugar
molecules via their hydroxyl groups
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 crosslinking of polysaccharides can result in very different properties, as
with plastics
DNA (polynucleotides)
 monomers: nucleotides (4 exist: abbreviated as A, T, C and G)
 linkage: phosphodiester linkage between the phosphate of one nucleotide
and the sugar of another (formed by dehydration synthesis)
 one strand of DNA pairs with another via
hydrogen bonding, resulting in a “double helix”
structure
Homework:
pg. 124 #4,6(top) #2,4;
pg. 128 #2,5,6;
pg. 131 #2,3