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Synthetic and Biological Polymers

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.

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Synthetic and Biological Polymers

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  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. Hydrocarbons ex: Alkanes • 1 – Meth- • 2 – Eth- • 3 – Prop- • 4 – But- • 5 – Pent- • 6 – Hex- • 7 – Hept- • 8– Oct- • 9– Non- • 10 – Dec- • 11– Undec- • 12 – Dodec-

  3. Hydrocarbons at Room Temperature • Liquid • Waxy 20 to 40 Carbons 40 or more Carbons • Gas • Methane • Ethane • Propane • Butane • Plastic 5 to 19 Carbons

  4. Melting Point • As the length of hydrocarbons get longer, the Melting Point grows Higher. Why?

  5. What other material properties change? • Viscosity • Hardness • Toughness • Flammability

  6. Bonding • Covalent • Ionic (NaCl) • Polar (H2O) • Van der Waals

  7. 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

  8. Example of addition polymers

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

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

  11. .. RO .. Mechanism • H2C CHCH3

  12. .. RO: Mechanism H2C CHCH3 •

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

  14. .. RO: Mechanism H2C CHCH3 H2C CHCH3 •

  15. .. RO: H2C CHCH3 Mechanism H2C CHCH3 H2C CHCH3 •

  16. .. RO: Mechanism H2C CHCH3 H2C CHCH3 H2C CHCH3 •

  17. .. RO: H2C CHCH3 Mechanism H2C CHCH3 H2C CHCH3 H2C CHCH3 •

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

  19. Important constitutions for synthetic polymers

  20. Supramolecular structure of polymers

  21. Structural properties of linear polymers: conformational flexibility and strength

  22. Molecular Structure of Polymers • Linear • High Density Polyethylene (HDPE), PVC, Nylon, Cotton • Branched • Low Density Polyethylene (LDPE) • Cross-linked • Rubber • Network • Kevlar, Epoxy

  23. Chain Length: 1000 - 2000 Low-Density Polyethylene (LDPE)

  24. Chain Length: 4,000 – 5,000 PVC – (polyvinyl chloride) More Polar  Stronger Bonding

  25. Chain Length: 10,000 – 100,000 High-Density Polyethylene (HDPE)

  26. Chain Length: 2-6 million Ultra-high-molecular-weight polyethylene (UHMWPE) Joint Replacement Helmet Gears

  27. Rubber Tree • Sap: • Sticky • Viscous • Gooey • Goodyear • Experiment • Luck • Profit ($0)

  28. Vulcanization

  29. 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

  30. Chain Length: 4,000 – 8,000 Polyethylene Terephthalate (PETE) “Polyester” Ester

  31. Kevlar Strong Network of Covalent Bonds And Polar Hydrogen Bonds

  32. Nylon

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

  34. 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

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

  36. Cotton Long Strands of Cellulose + Hydrogen Bonds Cellulose is the most common organic material on earth! It is also a primary constituent of wood and paper.

  37. Starch Polymers in Biology DNA Sugar Proteins

  38. 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

  39. Representation of the constitution of a protein

  40. Three D representation of the structure of a protein

  41. DNA

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

  43. Phosphate-sugar backbone holds the DNA macromolecule together

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

  45. Carbohydrates

  46. Endless Possibilities • New Functional Groups • Different Polymer Backbones

  47. Conclusions: • Polymers make up all sorts of materials that are all around us! • They can have a huge range or material properties based on their: • Functional Groups • Structure • Backbone • Keep thinking about how chemical interactions on the nano-scale correspond to material properties on the macro-scale

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