Chemistry 500 Dr. Hunter’s Class Topic 9.2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University1Chemistry 500: Chemistry in Modern LivingTopic 9: The World of Plastics and PolymersPolymer/Materials ScienceChemistry in Context, 2nd Edition: Chapter 10, Pages 319-350Chemistry in Context, 3rd Edition: Chapter 9, Pages 337-374Outline Notes by Dr. Allen D. Hunter, YSU Department ofChemistry, 2000.Chemistry 500 Dr. Hunter’s Class Topic 9.2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University2Outline9A CARBON ALLOTROPES................................................................................................................................................39B THE PLASTIC ECONOMY............................................................................................................................................49C POLYMERS.........................................................................................................................................................................59D SOME NATURAL POLYMERS....................................................................................................................................79E POLYETHYLENE..............................................................................................................................................................89F HIGHER ORDER POLYMER STRUCTURES........................................................................................................99G THE BIG SIX.....................................................................................................................................................................109H ADDITION POLYMERIZATION..............................................................................................................................139I CONDENSATION POLYMERIZATION.................................................................................................................149J POLYMER BONDS VS. DISCRETE MOLECULE BONDS..............................................................................159K THE STORY OF KEVLAR...........................................................................................................................................16Chemistry 500 Dr. Hunter’s Class Topic 9.2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University39A Carbon AllotropesØ Allotropes are different chemical forms of the same ElementØ Carbon is unique, especially in its tendency to form long chainsØ Graphics from Text: Figures 10.2 and 10.3 in 2nd Edition and9.2a, b, c in 3rd Edition, the allotropes of CarbonØ DiamondØ All covalent bondsØ GraphiteØ Covalent bonds within layers (i.e., arene like)Ø Van der Waals bonds between layersØ BuckminsterfullereneØ Covalent bonds within cages (i.e., arene like)Ø 5 and 6 membered ringsØ Van der Waals bonds between cagesChemistry 500 Dr. Hunter’s Class Topic 9.2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University49B The Plastic EconomyØ Scale of ProductionØ Graphics from Text: Figure 10.4 in 2nd Edition and 9.5 in 3rdEdition, Annual US production (in billions of pounds)Ø Approximately 100,000,000,000 pounds of plastics areproduced in year in USØ Regularly increasing productionØ Uses of plasticsØ To replace other materialsØ Lower cost and/or better performanceØ Ask Students: What materials to plastics replace inconsumer productsØ Group ActivityChemistry 500 Dr. Hunter’s Class Topic 9.2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University59C PolymersØ Starting Materials for plastic productionØ Fossil Fuel Starting MaterialsØ PetroleumØ Graphics from Text: Figure 10.12 in 2nd Edition and9.15 in 3rd Edition, the uses of a barrel of oilØ Natural GasØ CoalØ Biological Starting MaterialsØ Plant MaterialsØ Bacterial ProductsØ Animal ProductsChemistry 500 Dr. Hunter’s Class Topic 9.2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University6Ø MonomersØ The small molecules from which plastics are madeØ Must have a very low cost per pound (typically a few tens ofcents)Ø Relatively low molecular weights (typically from 28 to ahundred or so)Ø Constant structures in pure samplesØ Constant molecular weights in pure samplesØ PolymersØ Large molecules composed of many similar or identicalRepeating UnitsØ Must have quite low prices or will be replaced by othermaterialsØ Molecular Weights from thousands to millionsØ Variable structures even in pure samplesØ Variable molecular weights even in pure samplesChemistry 500 Dr. Hunter’s Class Topic 9.2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University79D Some Natural PolymersØ The bulk of living organisms (other than water) is composed ofnatural polymersØ Ask Students: What are some of the more common naturalpolymers?Ø Group ActivityChemistry 500 Dr. Hunter’s Class Topic 9.2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University89E PolyethyleneØ The most common plasticØ Over 20,000,000 tons are produced each year in USØ Found in plastic bags, construction materials, aircraft, etc.Ø Equation for synthesisH2C=CH2 + Catalyst → -CH2-CH2-CH2-CH2-CH2-CH2-Is equivalent to sayingH2C=CH2 + Catalyst → -[CH2-CH2]n-Ø At high temperatures the reaction can reverseØ DepolymerizationØ Occurs because π-bonds are stronger than σ-bondsChemistry 500 Dr. Hunter’s Class Topic 9.2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University99F Higher Order Polymer StructuresØ Backbone StructureØ The structure of the repeating units that link polymerstogetherØ Side ChainsØ Occur in variable frequency depending on synthetic methodsØ Occur in variable lengths depending on synthetic methodsØ Cross LinksØ Connect adjacent chainsØ High Density Polyethylene, HDPEØ Long relatively straight chainsØ Low Density Polyethylene, LDPEØ Highly branched StructuresChemistry 500 Dr. Hunter’s Class Topic 9.2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University109G The Big SixØ Five have long chains of carbon atoms in their backbones (i.e.,they are giant alkanes)Ø Graphics from Text: Table 10.1 and Figure 10.9 in 2nd Editionand Table 9.1 and Figure 9.11 in 3rd Edition, The Big SixØ LDPE prepared from EthyleneØ HDPE prepared from