3.12 Polymers

• what are addition polymers?

  Alkene monomers that are joined together to form a long, saturated molecule
• Why are polyalkenes non-biodegradable?

  chemically inert as there is no bond polarity so must be disposed of by burning or burying in landfill
• what are condensation polymers?

  monomers that are joined together by bonds formed from condensation reactions
• Why are condensation polymers biodegradable?

  can be hydrolysed and therefore broken into smaller fragments as they are readily attacked by nucleophiles to form there constituent monomers
• how are polyesters formed?

  dicarboxylic acids and diol to form an ester and water
• what is the linkage called in a polyester?

  ester linkage
• how are polyamides formed?

  dicarboxylic acid reacts with an amine to form an amide with water
• what is the linkage called in a polyamide?

  amide linkage
• how are polypeptides formed?

  when many amino acids react, water is released as the molecules join together forming a polypeptide
• how can you identify the monomer from a section of the polymer chain?

  look for the linkage - this is where the monomers have joined together so it needs to be broken to identify the monomer
• how can you identify the repeating unit from a section of the polymer chain?

  look along the chain and find the repeating pattern and isolate the section before it starts again
• what intermolecular forces are found in addition polymers?

  non-polar: strongest IMF is van der waals

  polar: strongest IMF is dipole-dipole
• what intermolecular forces are found in condensation polymers?

  Hydrogen bonded to NOF: Hydrogen bonding

  no hydrogen bonds: dipole-dipole
• what is the advantage of burning polymers?

  - releases a lot of energy which can be used to generate electricity

  - volume of rubbish is greatly reduced
• what is the disadvantage of burning polymers?

  - releases toxic gas

  - CO2 us produced on incineration which is a greenhouse gas
• what are the advantages of burying polymers?

  - most common method

  - cheap

  - little energy required
• what are the disadvantages of burying polymers?

  - landfill sites are becoming scarce

  - large amounts of land needed

  - polyalkenes can take hundreds of years to break down

  - methane is produced from decomposing waste (greenhouse gas)

  - unsightly

  - wastes raw material that may be non-renewable (crude oil)
• what are the advantages of recycling polymers?

  - save raw materials including crude oil

  - thermoplastic polymers can be melted down and reshaped

  - some plasticisers can be cracked into monomers and used to make new polymers
• what are the disadvantages of recycling polymers?

  - energy and resources are needed in collecting and sorting waste. it can be more expensive than incineration or landfill

  - polymers need to be recycled in the same types, which may be difficult to achieve

  - it is often hard to make the plastic you started with