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Exam 3 Histogram: Grade Frequency

05

101520253035

304 7 10 13 16 19 22 25 28

Bin

Freq

uenc

y

Frequency

Grade distribution for Exam 3

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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-styreneBiological polymers: DNA, proteins, carbohydrates

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Methods for making polymers

Addition polymerization and condensation polymerizationAddition 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

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Example of addition polymers

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200 °C200 °C2000 atm2000 atm

OO22

peroxidesperoxides

polyethylenepolyethylene

HH22CC CHCH22

CHCH22 CHCH22 CHCH22 CHCH22 CHCH22 CHCH22 CHCH22

Free-Radical AdditionPolymerization of Ethylene

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polypropylenepolypropylene

HH22CC CHCHCHCH33

CHCH CHCH CHCHCHCHCHCHCHCH CHCH

CHCH33 CHCH33 CHCH33 CHCH33 CHCH33 CHCH33 CHCH33

Free-Radical Polymerization of Propene

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••....

RORO....

HH22CC CHCHCHCH33

Mechanism

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HH22CC CHCHCHCH33••

....RORO:: Mechanism

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HH22CC CHCHCHCH33••

....RORO:: Mechanism

CHCHCHCH33HH22CC

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HH22CC CHCHCHCH33

HH22CC CHCHCHCH33••

....RORO:: Mechanism

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HH22CC CHCHCHCH33

HH22CC CHCHCHCH33••

....RORO:: Mechanism

CHCHCHCH33HH22CC

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HH22CC CHCHCHCH33

HH22CC CHCHCHCH33

•• HH22CC CHCHCHCH33

....RORO:: Mechanism

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HH22CC CHCHCHCH33

HH22CC CHCHCHCH33

•• HH22CC CHCHCHCH33

....RORO:: Mechanism

CHCHCHCH33HH22CC

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Likewise...

•H2C=CHCl polyvinyl chloride

•H2C=CHC6H5 polystyrene

•F2C=CF2 Teflon

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Important constitutions for synthetic polymers

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Supramolecular structure of polymers

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Structural properties of linear polymers: conformational flexibility and strength

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Cross linking adds tensile strength

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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 + H2O

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a smug Los Angeles businessman takes aside the baby-faced

Dustin Hoffman and declares,

Polymers in the movies

In the 1967 movie, "The Graduate”,

"I just want to say one word to you -- just one word -- 'plastics.' "

In 2005 we can replace ‘plastics’ with another word: ‘synthetic

polymers’

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QuickTime™ and aPhoto - JPEG decompressor

are needed to see this picture.

They're nylons, Benjamin.

Rembember f rom GChem?

Nylon is a condensation polymer made of the monomers adipic acid and hexamethylene diamine.

O OHO

OH

adipic acid

NH2H2N

hexamethylene diamine

+

nylon

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SupramolecularStructure of nylonIntermolecular hydrogen bonds give nylon enormous tensile strength

Hydrogen bonds between chains

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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 difference between amino acids is the R group

NH2

RO

HOH

The basic structure of an amino acid monomer

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Proteins: condensation polymers

Formed by condensation polymerization of amino acids

Monomers: 20 essential amino acids

Glycine (R = H) + Glycine First step toward poly(glycine)

NH2

CO2H

RHGeneral structure of an amino acid

R is the only variable group

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Representation of the constitution of a protein

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Three D representation of the structure of a protein

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DNA

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The monomers:

Adenine (A)

Thymine (T)

Guanine (G)

Cytosine (C)

Phosphate-Sugar (backbone) ofDNA

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Phosphate-sugar backbone holds the DNA macromolecule together

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

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Carbohydrates

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