Polymerization Reactions

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Polymerization Reactions
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What is Polymerization?

• Polymerization is a process in which very small
  molecules, called monomers, combine chemically
  with each other to produce a very large chainlike
  molecule, called a polymer.

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How are the pictures of DNA different? Identify
the trimer of DNA. What are the cross-linkers?
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The First Polymerization

• The first synthetic polymer was discovered in
  1909 by Leo Backeland, a Belgian-born US Chemist.
  
• It was marketed under the trademark Bakelite,
  which was made from phenol and formaldehyde.
• It became an important plastic and resin for
  adhesives, and paints.

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Polymerization Types

• There are two main types of Polymerization
  reactions
• Addition
• Condensation

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Think water, although that is not always the case
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Addition Polymerization

• In Addition Polymerization, monomers form without
  a by-product, such as water.

• The structure has one structural unit, or
  monomer, that occurs repeatedly.

• The monomer molecules may be all alike, or they
  may represent two, three, or more different
  compounds. The Addition Reaction involves only
  double and single bonded compounds.

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Addition Polymerization

• Through polymerization of ethylene (ethene),
  CH2CH2, the structure of the polymer can be
  represented by -(CH2CH2)n- where n can be several
  thousand.

• Example
• H H H H H H H H H H H H
• 
  
• CC CC CC gt C-CC-CC-C
• H H H H H H H H H H H H
  
• ethylene part of polyethylene

• In 1839, American chemist Charles Goodyear
  discovered
• that natural rubber could be cross-linked with
  sulfur.
• This process was known as vulcanization.

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How are Free Radicals Used in Polymerization?
Free-Radical Addition is another type of
polymerization reaction. This is when the
polymer is induced (started) by an initiator,
which is a compound that produces free radicals
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What Free Radicals Are NOT
Hey, these radicals Are still free! Dont They
need to be Arrested?
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What Free Radicals Are NOT
Ah, Out from under at last!!!
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Your math teacher would not approve
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What a Free Radical IS

• Free-radicals are species that have an unpaired
  electron.

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What does an unpaired electron mean?
Remember the electron configuration thing?
Well, an unpaired electron is when An orbital
has only an electron with one spin (either 1/2
or -1/2) Example 1s2 2s1 Example
1s22s22p5 In a compound an UNPAIRED electron
is one that is unbonded
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Condensation Polymerization

• In condensation polymerization, two functional
  groups of two different monomer molecules are
  joined together which produces a small molecule
  such as water.
• The monomers bond where the hydrogen atoms were
  taken out to produce water.
• In order to become a condensed polymer, the
  monomer molecules must have at least two
  functional groups.

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Condensation Polymerization

• The reaction between a carboxylic acid and an
  alcohol creates an ester.
• If the carboxylic acid and the alcohol were the
  monomers of the polymer, during polymerization,
  they would create polyester, and produce water.

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Condensation Polymerization

• Example of condensation polymerization
• Curing of concrete

• There are several types of materials that form by
  Condensation Polymerization, including nylon,
  polyesters, rayon, and spandex.

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