Depolymerization

Source: Wikipedia, the free encyclopedia.

Depolymerization (or depolymerisation) is the process of converting a polymer into a monomer or a mixture of monomers.[1] This process is driven by an increase in entropy.

Depolymerization of polystyrene via radical elimination mechanism

Ceiling temperature

The tendency of polymers to depolymerize is indicated by their ceiling temperature. At this temperature, the enthalpy of polymerization matches the entropy gained by converting a large molecule into monomers. Above the ceiling temperature, the rate of depolymerization is greater than the rate of polymerization, which inhibits the formation of the given polymer.[2]

Ceiling Temperatures of Common Organic Polymers
Polymer Ceiling Temperature (°C)[3] Monomer
polyethylene 610 CH2=CH2
polyisobutylene
 175 CH2=CMe2
polyisoprene (natural rubber) 466 CH2=C(Me)CH=CH2
poly(methyl methacrylate) 198 CH2=C(Me)CO2Me
polystyrene 395 PhCH=CH2
Polytetrafluoroethylene 1100 CF2=CF2

Applications

Depolymerization is a very common process. Digestion of food involves depolymerization of macromolecules, such as

1-hexene and heptane. Out of these, only ethylene can be used for polyethylene production, so other gases must be turned into ethylene, sold, or otherwise be destroyed or be disposed of by turning them into other products.[4]

Depolymerization is also related to production of chemicals and fuels from

acid catalyst
:

H(C6H10O5)nOH + (n - 1) H2O → n C6H12O6


See also

References

  1. ^ Depolymerization, IUPAC Goldbook
  2. ISBN 978-1-4398-0953-2
    .
  3. ISBN 978-0-19-512444-6
    .
  4. doi:10.4067/S0717-97072011000200006
    .

External links

Look up depolymerization in Wiktionary, the free dictionary.


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