3.8.3

Effects of Side-Chains on Polymers

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Effects of Side-Chains on Polymers

Side-chains & intermolecular forces can impact the properties of polymers. Two examples are PTFE and Kevlar.

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PTFE

  • Polytetrafluoroethylene (PTFE) is a polymer of tetrafluoroethylene.
  • Fluorine is a very electronegative atom, which reduces the strength of the van der Waals forces between neighbouring PTFE strands.
    • This is because the electrons are held closely to the fluorine atom.
  • Each monomer subunit is also symmetrical. This eliminates any overall charge across the molecules.
  • This makes PTFE non-polar.
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PTFE - 2

  • PTFE molecules have small side chains. The side chains are just individual fluroine atoms.
  • This allows PTFE strands to pack closely together.
  • Even though the strength of the van der Waals forces is reduced in PTFE, many forces can form between the closely packed strands.
    • This means PTFE has a fairly high melting point.
  • Together the high melting point and hydrophobic nature make PTFE a useful non-stick material in cookware.
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Kevlar

  • Kevlar is a very strong polyamide made from benzene-1,4-dicarboxylic acid and 1,4-diaminobenzene monomers.
  • Neighbouring strands of kevlar can form hydrogen bonds.
    • These bonds occur between the CO group of one monomer and the NH group of the monomer on a different chain.
  • Kevlar has a high tensile strength-to-weight ratio (it is about 5 times stronger than an equal weight of steel).
  • This makes it useful for many applications from bicycle tires to sails to body armour.

Jump to other topics

1Physical Chemistry

1.1Atoms, Molecules & Stoichiometry

1.2Atomic Structure

1.3Chemical Bonding

1.4States of Matter

1.5Chemical Energetics

1.6Electrochemistry

1.7Equilibria

1.8Partition Coefficient

1.9Reaction Kinetics

2Inorganic Chemistry

3Organic Chemistry & Analysis

3.1Introduction to Organic Chemistry

3.2Hydrocarbons

3.3Halogen Derivatives

3.4Hydroxy Compounds

3.5Carbonyl Compounds

3.6Carboxylic Acids & Derivatives

3.7Nitrogen Compounds

3.8Polymerisation

3.9Analytical Techniques

3.10Organic Synthesis

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