Exam 3 Histogram: Grade Frequency

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

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

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

7. .. RO .. Mechanism • H2C CHCH3

8. .. RO: Mechanism H2C CHCH3 •

9. .. RO: H2C CHCH3 Mechanism H2C CHCH3 •

10. .. RO: Mechanism H2C CHCH3 H2C CHCH3 •

11. .. RO: H2C CHCH3 Mechanism H2C CHCH3 H2C CHCH3 •

12. .. RO: Mechanism H2C CHCH3 H2C CHCH3 H2C CHCH3 •

13. .. RO: H2C CHCH3 Mechanism H2C CHCH3 H2C CHCH3 H2C CHCH3 •

14. Likewise... • H2C=CHCl polyvinyl chloride • H2C=CHC6H5 polystyrene • F2C=CF2 Teflon

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. 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’

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

26. General structure of an amino acid Proteins: condensation polymers Formed by condensation polymerization of amino acids Monomers: 20 essential amino acids R is the only variable group First step toward poly(glycine) Glycine (R = H) + Glycine

27. Representation of the constitution of a protein

28. Three D representation of the structure of a protein

29. DNA

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