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Chapter 10 Polymers: Giants Among Molecules. Macromolecules. Compared to other molecules, they are enormous Molar mass: 10,000–1,000,000+ g/mol Not visible to naked eye Polymers: made from smaller pieces Monomer: small chemical building block

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Chapter 10 polymers giants among molecules

Chapter 10 Polymers: Giants Among Molecules


  • Compared to other molecules, they are enormous

    • Molar mass: 10,000–1,000,000+ g/mol

    • Not visible to naked eye

  • Polymers: made from smaller pieces

    • Monomer: small chemical building block

  • Polymerization: process in which monomers are converted to polymers

Chapter 10

Natural polymers
Natural Polymers

  • Found extensively in nature

    • Life could not exist without polymers

    • Come in various shapes and sizes

  • Made of sugars, amino acids, nucleic acids

  • Examples: wool, silk, cotton, wood, paper

Chapter 10


  • React cellulose with nitric acid

  • Used for first films and billiard balls

  • Highly flammable

    • Used in smokeless gunpowder

  • No longer in use

Chapter 10

Synthetic polymers
Synthetic Polymers

  • Made from monomer synthesized from fossil fuels

  • First manufactured shortly before World War II

  • Synthesized using addition reactions

    • Add monomer to end of polymer chain

    • Build very large polymers

Chapter 10


  • Cheapest and simplest synthetic polymer

    • Made from CH2=CH2

    • Invented shortly before World War II

  • Has two forms

    • High-density polyethylene (HDPE)

    • Low-density polyethylene (LDPE)

Chapter 10

Thermoplastic and thermosetting polymers
Thermoplastic and Thermosetting Polymers

  • Thermoplastic polymer: softened by heat or pressure and reshaped

    • Polyethylene

  • Thermosetting: harden permanently when formed

    • Once formed, cannot be reshaped

Chapter 10


  • Change a –H to –CH3

  • Harder and has higher melting point than polyethylene

Chapter 10


  • Change a –H to benzene ring

  • Widely used

    • Disposable cups

    • Insulation

Chapter 10

Vinyl polymers
Vinyl Polymers

  • Change a –H to –Cl

  • Tough thermoplastic

    • Polyvinyl chloride (PVC)

Chapter 10


  • Change all –H to –F

    • C–F very strong. Resists heat and chemicals

    • Makes very unreactive polymer

Chapter 10

Other polymers
Other Polymers

Chapter 10

Practice problems
Practice Problems

Chapter 10


  • Pre–World War II

    • Came from natural sources in S.E. Asia

    • Japan cut off supply during World War II

  • Made of isoprene

  • Chemists learned to make it during World War II

Chapter 10


  • Link individual polymer strands with S atoms

  • Makes rubber stronger

    • Can be used on natural or synthetic rubber

  • Elastomers: materials that stretch and snap back

    • Key property of rubber

Chapter 10

Synthetic rubber
Synthetic Rubber

  • Use butadiene

    • CH2=CH-CH=CH2

  • Polychloroprene: substitute –Cl for a –H

  • Change the properties for other uses

    • Tend to be resistant to chemicals

Chapter 10


  • Add two or more different monomers

  • Uses addition reaction

  • Allows for modification of polymer’s properties

  • Styrene–butadiene rubber (SBR)

    • 75% butadiene/25% styrene mix

    • Used mainly for tires

Chapter 10

Condensation polymers
Condensation Polymers

  • Part of the monomer will not be incorporated into the final material

    • Typically a small molecule like water

  • Formula of the repeating unit not same as monomer

  • Used to produce nylon and polyesters

Chapter 10

Composite materials
Composite Materials

  • Use high-strength polymers

    • Could include glass, graphite, or ceramics

  • Hold everything together with polymers

    • Typically thermosetting, condensation polymer

  • Result is a very strong, lightweight material

    • Used in cars, sports gear, boats

Chapter 10

Silicone polymers
Silicone Polymers

  • Based on alternating Si and O atoms

  • Heat stable and resistant to most chemicals

  • Properties depend on length of polymer

  • Many uses

    • Shoe polish, coatings on raincoats, Silly Putty

Chapter 10

Properties of polymers
Properties of Polymers

  • Crystalline: polymers line up

    • High tensile strength

    • Make good synthetic fibers

  • Amorphous: polymers randomly oriented

    • Make good elastomers

  • Some material has both types of polymers mixed together

    • Flexibility and rigidity

Chapter 10

Chapter 10 polymers giants among molecules

  • Glass transition temperature, Tg

    • Above Tg, polymer is rubbery and tough

    • Below Tg, polymer hard, stiff, and brittle

  • Determine where polymer will be used

  • What type of Tg do you want your plastic coffee cup to be?

Chapter 10

Fiber forming properties
Fiber-Forming Properties

  • Majority of fabrics made of synthetic polymers

  • Tend to last longer, easier to care for

    • Nylon vs. silk

  • Also may make mixtures

    • Cotton/polyester blends

Chapter 10

Disposal of plastics
Disposal of Plastics

  • Do not degrade readily

    • Designed to be durable

    • Last a long time

  • Make up 8% by mass of landfills

    • But make up 21% by volume

    • Tend to fill up landfills

  • Incinerate plastics

    • Produce lots of heat when burned

    • May give off unwanted by-products

  • Degradable plastics

    • Photodegradable: need light to break down

    • Biodegradable: break down in presence of light

    • Do not want to degrade too soon

Chapter 10


  • Collect, sort, chop, melt, and then remold plastic

  • Requires strong community cooperation

Chapter 10


  • Make plastic more flexible and less brittle

    • Lower Tg

    • Tend to be lost as plastic ages

  • Most common plasticizers today based on phthalic acid

Chapter 10