Degradable polymers
Introduced| English | Meaning |
|---|---|
| non-polar/nɒn ˈpəʊlə/ | Having no significant separation of electric charge in a bond, or no overall permanent dipole in a molecule. |
| biodegrade/ˌbaɪəʊdɪˈɡreɪd/ | biodegrade |
| photodegradable/ˌfəʊtəʊdɪˈɡreɪdəbl/ | photodegradable |
| hydrolysis/haɪˈdrɒləsɪs/ | Breaking chemical bonds by reaction with water. |
Plastics that break down
- Some polymers break down in the environment; others barely do.
- It depends on the bonds in the chain.
- This matters for waste and pollution.
Degradable polymer route
Follow how polymer structure controls breakdown.
Polymers that can be broken down by microbes or hydrolysis are described as ______.
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They reduce plastic waste.
Condensation polymers such as polyesters can be hydrolysed and so are more easily degraded than addition polymers.
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The ester/amide links can be broken.
What degrades, and what doesn't
- poly(alkene)s are chemically inert — only strong, non-polar 非极性 C–C and C–H bonds — so they are hard to biodegrade 生物降解 and last a long time.
- some polymers are made photodegradable 光降解 (light breaks them down).
- polyesters and polyamides are biodegradable — their ester and amide links can be broken by acidic or alkaline hydrolysis 水解.
The nylon rope trick: a thread of nylon (a polyamide) forms where two reactant solutions meet and can be pulled out as one long strand (it is pink here from an indicator)
Poly(alkene)s are hard to biodegrade because they have:
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With no polar links to attack, microbes cannot easily break poly(alkene)s down.
Polyesters and polyamides are biodegradable because:
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Acidic or alkaline hydrolysis breaks the ester/amide links, so these polymers degrade.
Some polymers are made photodegradable so that light can break them down.
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Photodegradable polymers are designed to be broken down by light.
Why degradability matters
- Condensation polymers can be hydrolysed, so they break down more easily than addition polymers.
- This reduces long-lived plastic waste.
Designing greener plastics
- Biodegradable and photodegradable polymers are designed to break down after use.
- They ease disposal but can cost more to make.
You've got it
- poly(alkene)s = inert (strong non-polar bonds) → hard to biodegrade
- some polymers are photodegradable (broken by light)
- polyesters/polyamides are biodegradable — their links can be hydrolysed