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