Polymers
Introduced| English | Meaning |
|---|---|
| polymers/ˈpɒlɪməz/ | A large molecule made from many linked repeating units derived from smaller molecules. |
| monomer/ˈmɒnəʊmə/ | A molecule that can join with other molecules to form a polymer. |
| addition polymerisation/əˈdɪʃn ˌpɒlɪməraɪˈzeɪʃn/ | The joining of unsaturated monomers into a polymer without forming a separate small-molecule product. |
| non-biodegradable/nɒn ˌbaɪəʊdɪˈɡreɪdəbl/ | non-biodegradable |
Tiny units, giant chains
- Plastics are everywhere — and they're all built the same way, by joining small molecules into long chains.
- These long-chain molecules are polymers 聚合物.
A monomer is:
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Monomers join to form polymers.
A polymer is:
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Polymers are long chains of repeating units.
Monomers 单体 and polymers
- A monomer is a small molecule that can join to others.
- A polymer is a very long molecule made of many monomers joined together.
Many small monomers join to make one long polymer chain.
Making a polymer
Small monomers join into a long chain — the basis of all plastics.
In addition polymerisation, the monomers are:
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Alkene double bonds open and join.
Many ethene molecules join to form the polymer poly(______).
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Poly(ethene) is polythene.
Addition polymerisation 加聚
- In addition polymerisation, many alkene monomers add together.
- Their double bonds open up and join, with no other product formed.
- Example: many ethene molecules → poly(ethene) (polythene).
In addition polymerisation the C=C bonds open up and many ethene monomers join into one long poly(ethene) chain
Most addition polymers are non-biodegradable.
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They do not rot, so they build up as waste.
The plastic problem
- Most addition polymers are non-biodegradable 不可生物降解的 — they don't rot away.
- They build up as waste, so recycling and careful disposal matter.
Worked example. Ethene (CH₂=CH₂) has a double bond. Under pressure, thousands of ethene molecules open their double bonds and join into one long chain — poly(ethene), the plastic in bags and bottles.
You've got it
- a polymer is a long chain made of many small monomers
- addition polymerisation: alkene monomers' double bonds open and join (no other product)
- e.g. ethene → poly(ethene); most are non-biodegradable, so recycling matters
Write from a double bond that opens
- Many ethene molecules are joined into one chain.
- The product is poly(ethene).
What happens to the double bond as the chain forms?
Addition polymerisation uses the opened double bond to link monomers.
What happens to the double bond when ethene polymerises?
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The monomer's double bond becomes the link in the chain.