C2-Material Choices

C2-Material Choices

1. Materials

   • Natural
     • Made/obtained from living things
     • Cotton, paper, silk, wool
   • Synthetic
     • Produced by chemical synthesis
   • Crude Oil
     • Hydrocarbons
       • Different hydrocarbons=different boiling points=different molecular chains
         • Strength of forces between molecules increases as length increses
           • More energy to break
     • Fractional distillation
     • Fuels, lubricants and raw materials for chemical synthesis
       • Most=fuels
       • Small amounts=synthesis
   • Materials we use: Chemicals&mixtures of chemicals
     • Metals, Polymers, Ceramics

2. Properties and uses of materials

3. Polymerisation

   • Small hydrocarbon molecules=joined together
   • Monomer->Polymer
   • Using
     • Create wide range of different materials
       • Different properties and uses
     • Traditional materials=replaced by polymers=superior properties
       • Polyethene replaced paper for bags
       • PVC replaced wood for window frames
   • Modifications in Polymers
     • Increasing chain length
       • Stroger
     • Cross-linking
       • Vulcanisation
         • Sulphur atoms=rubber molecules
           • Tyres/conveyor belts
       • Atoms bonding between molecules
         • Can't move=harder
     • Platicisers
       • Softer/flexible
       • Sits between molecules=forces apart
         • Weaker
       • Toys
     • Crystallisation
       • Packing molecules together
         • Crystalline
           • Intermolecular forces=stronger
             • Stronger, denser, higher melting point

4. Nanotechnology

   • Properties of Nanoscale materials
   • Nanoscience
     • Study of materials=1-100nm
   • Nanotechnology
     • Science of building things on tiny scale
   • Nanoscale
     • Naturally occurring= liposomes& sea spray
     • Accidentally formed
       • Smallest particles= combustion of fuels
   • Specific jobs
     • Titanium dioxide
       • Absorbing uv= sunscreens
     • Use in medicine, dentistry, car industry, product-specific catalyst
   • Antibacterial fibres
     • Greater awareness of contact disease transmission and personal hygiene=development of antibacterial fibres
     • Silver nanoparticles
       • Destroy many types of bacteria
       • Scientists=developed antibacterial fibres containing silver nanoparticles
       • Silver oxide fibre technology
         • Antibacterial properties=garments fresh
   • Sports
     • Golf clubs
       • Lighter, stronger, more efficient
       • Nanometals
         • Crystalline structure-4*stronger than metal
       • Straighter lines
     • Tennis Racket
       • Nanoscale silicon dioxide crystals
       • increase performance, doesn't change weight
   • Evaluating

5. Molecular structure of materials

   • Properties
     • How particles arranged
   • Natural rubber
     • Flexible
     • Tangled mass of long-chain molecules
     • Atoms=strong covalent bonds
       • Weak forces between molecules
         • Slide over=stretch
     • Low melting point
   • Strong forces between molecules
     • High melting points
     • Molecules can't slide=rigid&not stretchy