Grade distribution for Exam 3 35 30 25

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

Synthetic and Biological 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

Free-Radical Addition. Polymerization of Ethylene H 2 C CH 2 200 °C 2000 atm CH 2 O 2 peroxides CH 2 polyethylene 5

Free-Radical Polymerization of Propene H 2 C CH CH CH 3 CHCH 3 CH CH CH 3 CH 3 polypropylene 6

. . • RO. . H 2 C Mechanism CHCH 3 7

. . RO: H 2 C Mechanism CHCH 3 • 8

. . RO: H 2 C Mechanism CHCH 3 • H 2 C CHCH 3 9

. . RO: H 2 C Mechanism CHCH 3 H 2 C CHCH 3 • 10

. . RO: H 2 C Mechanism CHCH 3 H 2 C CHCH 3 • H 2 C CHCH 3 11

. . RO: H 2 C Mechanism CHCH 3 H 2 C CHCH 3 • 12

. . RO: H 2 C Mechanism CHCH 3 H 2 C CHCH 3 • H 2 C CHCH 3 13

Likewise. . . • H 2 C=CHCl • H 2 C=CHC 6 H 5 • F 2 C=CF 2 polyvinyl chloride polystyrene Teflon 14

Important constitutions for synthetic polymers 15

Supramolecular structure of polymers 16

Structural properties of linear polymers: conformational flexibility and strength 17

Cross linking adds tensile strength 18

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

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Hydrogen bonds between chains Supramolecular Structure of nylon Intermolecular hydrogen bonds give nylon enormous tensile strength 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 23

Proteins: amino acid monomers The basic structure of an amino acid monomer The difference between amino acids is the R group 24

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Proteins: condensation polymers Formed by condensation polymerization of amino acids 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) 26

Representation of the constitution of a protein 27

Three D representation of the structure of a protein 28

DNA 29

Thymine (T) The monomers: Adenine (A) Cytosine (C) Guanine (G) Phosphate. Sugar (backbone) of DNA 30

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 32

Carbohydrates 33

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