Polymers

• What is condensation polymerisation?

  Usually involves 2 different types of monomer. Each monomer has at least 2 functional groups. Each functional group reacts with a group on another monomer to form a link, creating polymer chains. Each time link formed, small molecule lost (h20).
• How are polyamides produced?

  Reactions between dicarboxylic acids & diamines. Carboxyl group of dicarboxylic acid reacts with amino group of diamine to form amide link. H20 lost each time amide link formed (condensation reaction).
• Properties of nylon:


  Strong & resistant to abrasion so used in clothing, carpet, rope, airbags & parachutes. (Polyamide).
• Properties of Kevlar:

  Light & very strong-used in bulletproof vests, boat construction, car tyres & lightweight sports equipment.
• How are polypeptides produced?

  Amino acids contain amine & carboxylic acid groups. Can react to form polyamides. Polymers between amino acids called peptides. Self-polymerisation.
• How are polyesters produced?

  Carboxyl groups of dicarboxylic acids react with hydroxyl groups of diols to form ester links. E.g, Terylene (PET).
• Properties of Terylene:

  Some forms stable at both hot & cold temperatures-useful for creating containers for ready meals. Other forms make plastic bottles, clothing, sheets & sails.
• How is hydrolysis improved in lab conditions?

  Just H20 too slow, in lab done with acid or alkali. Polyamides hydrolysed more easily in acidic conditions & polyesters hydrolysed more easily in basic conditions.
• Describe the bonding between polymer chains:

  Condensation polymers stronger & more rigid than addition polymers- condensation polymers made of chains containing polar bonds. So as well as van der waals forces, there's permanent dipole-dipole forces & strong hydrogen bonds between polymer chains.
• Biodegradability of polyalkenes:

  Polyalkenes chemically inert. Bonds between repeating units non-polar, so aren't susceptible to attack by nucleophiles. Chemically inert (unreactive) is advantage when polymers used, e.g, polystyrene cup won't react with coffee. Disadvantage: non-biodegradable (bonds in polymer can't be hydrolysed & won't break down naturally).
• How can condensation polymers be broken down?

  Hydrolysis- bonds between repeating units are polar & susceptible to attack by nucleophiles such as water. Bonds can be hydrolysed so biodegradable-process very slow .
• Evaluate burying waste plastic:

  Cheap & easy method of waste disposal. Requires areas of land, as waste decomposes it can release methane & also toxins that can be washed away & contaminate water supplies. Used when plastic difficult to separate from other waste, too difficult to technically recycle or not in sufficient quantities to make separation financially worthwhile.
• Evaluate burning waste plastic:

  Heat used to generate electricity. Process carefully controlled to reduce toxic gases. Waste gases from combustion passed through scrubbers which can neutralise gases such as HCl by allowing them to react with a base. (Waste gases contribute to greenhouse effect).
• Advantages of recycling plastics:

  Reduces amount of waste in landfill, saves raw materials (oil is non-renewable), produces less CO2 emissions than burning plastic, cost of recycling lower than making plastics from scratch.
• Disadvantages of recycling plastics:

  Technically hard to recycle plastics, often can't remake plastic you started with, plastic can be easily contaminated during recycling process & collecting, sorting & processing plastic is more expensive than burning/landfill.
• How are plastics recycled?

  Many plastics made from non-renewable oil fractions. After sorting into different types, some plastics melted & remoulded, while others cracked into monomers-can make more plastics or other chemicals.
• What type of condensation polymer is Nylon 6,6?

  Polyamide.