polymers Flashcards
What is addition polymerisation?
Long chain molecules made from joining together many shorter molecules (monomers) with nothing else produced.
Examples include poly(ethene), PVC, and poly(propene)
What is condensation polymerisation?
Long chain molecules made from joining together many shorter molecules (monomers) with some small molecule also formed (e.g. water).
Examples include polyesters (e.g. terylene) and polyamides (e.g. nylon, Kevlar)
What are the monomers involved in addition polymerisation?
Alkenes, which are molecules with C=C bonds.
Alkenes serve as the building blocks for addition polymers.
What are the monomers involved in condensation polymerisation?
Usually 2 different monomers with 2 different functional groups:
* Dicarboxylic acids with diols (polyesters)
* Dicarboxylic acids with diamines (polyamides)
* Amino acids (polyamides/polypeptides)
These combinations lead to the formation of polymers like nylon and terylene.
What is the reaction for forming a polyester?
Dicarboxylic acid + diol → polyester. Water is released and an ester link is formed.
This process illustrates the condensation polymerisation mechanism.
What is the reaction for forming a polyamide?
Dicarboxylic acid + diamine → polyamide. Water is released and an amide link is formed.
This reaction is key in the formation of materials like nylon and Kevlar.
What is the formation of polyamides from amino acids?
Amino acid + amino acid → polyamide. Water is released and an amide (peptide) link is formed.
This process is essential in forming proteins.
What are the uses of nylon?
Used in clothing due to its strong, flexible, and stretchy fibres.
Nylon is widely adopted in textile applications.
What are the characteristics of Kevlar?
Strength is due to rigid chains and flat aromatic rings that pack together, held by strong intermolecular forces.
Kevlar is used in bulletproof vests and anti-stab clothing.
Are polyalkenes biodegradable?
No, polyalkenes are not biodegradable.
They are long-chain alkane molecules that are inert.
How are polyalkenes typically disposed of?
Disposed of in landfill sites, incineration, or some may be melted down and remoulded.
The disposal methods reflect their non-biodegradable nature.
Are condensation polymers potentially biodegradable?
Yes, they are potentially biodegradable if broken down by hydrolysis.
Hydrolysis reverses the polymerisation process and can break down polar bonds.
What is the advantage of recycling polymers?
Saves using crude oil, which is expensive and diminishing, and uses less energy in refining.
Recycling helps mitigate environmental impact.
What are the disadvantages of recycling polymers?
Plastics need to be collected, transported, and sorted, which uses energy and manpower, making it expensive.
These processes can offset some environmental benefits.
What is a consequence of burning polyalkenes?
Produces energy but may release poisonous carbon monoxide if combustion is incomplete.
This adds to carbon dioxide levels in the atmosphere.
