Grade distribution for Exam 3
Exam 3 Histogram:
Grade Frequency
35
30
25
20
15
10
5
0
4 7 10 13 16 19 22 25 28 30
Bin
Frequency
1

Synthetic and Biological Polymers
Polymers: Macromolecules formed by the covalent attachment of a set of small molecules termed monomers.
Polymers are classified as:
(1) Man-made or synthetic polymers that are synthesized in the laboratory;
(2) Biological polymer that are found in nature.
Synthetic polymers: nylon, poly-ethylene, poly-styrene
Biological polymers: DNA, proteins, carbohydrates
2

Methods for making polymers
Addition polymerization and condensation polymerization
Addition polymerization : monomers react to form a polymer without net loss of atoms.
Most common form: free radical chain reaction of ethylenes n monomers one polymer molecule
3

Example of addition polymers
4

C CH
2000 atm

C CH CH
CH CH CH CH CH

..
RO • •
C CH CH
Mechanism

..
RO : :
• •
CH
Mechanism

..
RO : :
CH
• •
CH
CH CH
Mechanism

..
RO : :
CH CH
C CH CH
• •
Mechanism

..
RO : :
Mechanism
CH CH
C CH CH
• •
CH CH

..
RO : :
CH CH
C CH CH
C CH
• •
CH
Mechanism

..
RO : :
CH CH
C CH CH
C CH CH
• •
Mechanism
CH CH

Likewise...
2
2
6
5
2
2

15

16

Structural properties of linear polymers: conformational flexibility and strength
17

Cross linking adds tensile strength
18

Condensation polymerization
Condensation polymerization: the polymer grows from monomers by splitting off a small molecule such as water or carbon dioxide.
Example: formation of amide links and loss of water
Monomers
First unit of polymer + H
2
O
19

Polymers in the movies
In the 1967 movie, "The Graduate”, a smug Los Angeles businessman takes aside the baby-faced
Dustin Hoffman and declares,
"I just want to say one word to you -- just one word -- 'plastics .' !
"
In 2005 we can replace ‘plastics’ with another word: ‘synthetic polymers’
20

They're nylons, Benjamin.
Rembember from GChem?
Nylon is a condensation polymer made of the monomers adipic acid and hexamethylene diamine.
O OH
O
OH adipic acid
+
H
2
N hexamethylene diamine
NH
2 nylon
21

Supramolecular
Structure of nylon
Intermolecular hydrogen bonds give nylon enormous tensile strength
Hydrogen bonds between chains
22

Biopolymers
Nucleic acid polymers (DNA, RNA)
Amino acids polymers (Proteins)
Sugar polymers (Carbohydrates)
Genetic information for the cell: DNA
Structural strength and catalysis: Proteins
Energy source: Carbohydrates
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Proteins: amino acid monomers
The basic structure of an amino acid monomer
HO
O
NH
2
H
R
The difference between amino acids is the R group

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Proteins: condensation polymers
Formed by condensation polymerization of amino acids
H
NH
2
R
CO
2
H
Monomers: 20 essential amino acids
General structure of an amino acid
R is the only variable group
Glycine (R = H) + Glycine
First step toward poly(glycine)
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Representation of the constitution of a protein
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Three D representation of the structure of a protein
28

The monomers:
Adenine (A)
Guanine (G)
Phosphate-
Sugar (backbone) of
DNA
Thymine (T)
Cytosine (C)
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Phosphatesugar backbone holds the DNA macromolecule together
31

One strand unwinds to duplicate its complement via a polymerization of the monomers
C, G, A and T
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