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Addition Polymers
Appears in
Concepts tested here
- Polyisobutylene monomer
- Teflon from tetrafluoroethylene
All Questions
2002 AIPMT 1 question
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Monomer of
is : -The repeating unit $-C(CH_3)_2-CH_2-$ has a carbon with two methyl groups next to a $CH_2$.
Opening the double bond of $CH_2=C(CH_3)_2$ gives exactly this unit: $n\,CH_2=C(CH_3)_2 \rightarrow [-CH_2-C(CH_3)_2-]_n$
$CH_2=C(CH_3)_2$ is 2-methylpropene (isobutylene). The polymer is polyisobutylene, used in butyl rubber.
Propylene would give $[-CH_2-CH(CH_3)-]_n$ with only one methyl per unit.
So the monomer is 2-methyl propene.
2000 AIPMT 1 question
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$CF_2=CF_2$ is monomer of :Tetrafluoroethylene, $CF_2=CF_2$, polymerises (free radical, under pressure) to polytetrafluoroethylene (PTFE), known as Teflon:
$n\,CF_2=CF_2 \rightarrow [-CF_2-CF_2-]_n$
Teflon is chemically inert and heat resistant, and is used for non-stick cookware.
Orlon is from acrylonitrile, polythene from ethene, and nylon-6 from caprolactam.