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Grade distribution for Exam 3

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

2 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

3 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

4 Example of addition polymers

5 Free-Radical AdditionPolymerization of Ethylene
H2C CH2 200 °C 2000 atm O2 peroxides CH2 polyethylene 6

6 Free-Radical Polymerization of Propene
H2C CHCH3 CH CH3 polypropylene 6

7 .. RO Mechanism H2C CHCH3 7

8 .. RO: Mechanism H2C CHCH3 9

9 .. RO: Mechanism H2C CHCH3 CHCH3 H2C 10

10 .. RO: Mechanism H2C CHCH3 H2C CHCH3 10

11 .. RO: Mechanism H2C CHCH3 H2C CHCH3 CHCH3 H2C 10

12 .. RO: Mechanism H2C CHCH3 H2C CHCH3 H2C CHCH3 10

13 .. RO: Mechanism H2C CHCH3 H2C CHCH3 H2C CHCH3 CHCH3 H2C 10

14 Likewise... H2C=CHCl polyvinyl chloride H2C=CHC6H5 polystyrene
F2C=CF Teflon 19

15 Important constitutions for synthetic polymers

16 Supramolecular structure of polymers

17 Structural properties of linear polymers: conformational flexibility and strength

18 Cross linking adds tensile strength

19 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

20 In the 1967 movie, "The Graduate”,
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’

21

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

23 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

24 Proteins: amino acid monomers
The basic structure of an amino acid monomer The difference between amino acids is the R group 4

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26 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)

27 Representation of the constitution of a protein

28 Three D representation of the structure of a protein

29 DNA 4

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

31 Phosphate-sugar backbone holds the DNA macromolecule together

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

33 Carbohydrates 4

34


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