Polymeric Materials Molecular View

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Polymeric Materials Molecular View

• MFG 355

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Fundamentals of Matter

• Periodic Table
• Arranged by number of Protons
• Metals (lose electrons)
• Non-metals (gain electrons)

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Fundamentals of Matter

• Electrons
• Shells (n1,2,3,4,5) rows on periodic table
• Orbitals (s,p,d,f) columns on periodic table

s
p
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Basic Organic Chemistry

• Contains Carbon
• Carbon has 4 bonds in every molecule
• Valence bonds (number of bonds formed)
• Carbon4, Nitrogen3, Oxygen2, Chlorine1,
  Hydrogen1

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Basic Organic Chemistry
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Bonding (attractions)
Function of distance between atoms
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Bonding (attractions)

• Ionic Metal w/ Non-metal

-

Cl
Na
Transfer of electron
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Metal Atom
Non-Metal Atom
Electrons have been transferred
Negative (-) charged non-metal atom
Positive () charged metal atom
Ionic Bonding
Combination of a metal and a non-metal atom to
create an ionic bond material
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-

-
Ionic Bonds Negatively Charged Non-Metal
Particle Positively Charged Metal Particle
Part
-

-


-

-
-

-

Crystal structure showing charged metal and
non-metal particles and the ionic bonds between
them
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Bonding (attractions)

• Metallic Metal w/ Metal

Cr
Fe
Sea of electrons
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Metallic Bonding
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Bonding (attractions)

• Covalent Non-metal w/ Non-metal

Cl
Shared electrons
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Bonding (attractions)

• Secondary bonds
• Polar bond/Hydrogen bond
• One atom in a covalent bond is more negative than
  the other
• Atoms that cause polar bonding F, O, N, Cl

d-
d
Partial charges
O
C
Unequal sharing
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Crystalline Region
Non-Metal Atoms
Part
Amorphous Region
Covalent Bond (shared electrons)
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Periodic Table of the Elements
Metals
Non-Metals
Ceramics (Ionic Bonds)
Polymers (Covalent Bonds)
Metals (Metallic Bonds)
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Hydrogen (polar) Bonding
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Polymers

• Polarity in polymers
• Atoms that result in polarity F, O, N, Cl

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Functional groups
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Aromaticity
Increasing Aromaticity
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Polymers

• MonomersPolymers

Monomer
Polymer
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Polymers

• Carbon based and silicon based
• Almost all polymers are based on carbon
• Silicones and related polymers are the only
  silicone based polymers

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Addition Polymerization

• Mechanism
• Monomer in vessels (temperature and pressure)
• Initiatorfree radicals
• Attack CC (p bond)
• Bond and make new free radical
• New p bond reaction
• New free radical created
• Continuation
• Termination

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Addition Polymerization
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Addition Polymerization
Initiation and growth
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Addition polymerization
Initiator
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Addition Polymerization

• Chain TerminationUnreacted end, another chain

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Addition Polymerization

• Chain TerminationUnreacted Peroxide

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Addition Polymerization

• Chain TerminationOzone Quench

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Addition Polymerization

• Copolymers from Addition Polymerization
• Block Copolymer
• Random Copolymer
• Regular Copolymer
• Graft Copolymer

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Condensation Polymerization

• Mechanism
• Monomers (2)
• Each has two reactive sites
• Monomer ends react
• Condensation
• Removal of condensate
• Chain termination ends reaction

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Condensation Polymerization

• Monomers/Polymers

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Making a polyamide (nylon)
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Condensation Polymerization

• Chain termination

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Making a polyester
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Addition vs. Condensation
Condensation polymerization
Addition polymerization

• Polymer Growth Mechanism
• Dependence on previous step
• Initiator needed
• Type of monomer
• Number of active sites (functional groups) per
  monomer
• Number of different types of monomers needed to
  form polymer
• By-product formed
• Basic (polymer repeat unit) representation
• Polymer chain characteristics
• Branching

• Chain reaction
• Yesdependent sequential events
• Yes
• Contains carbon-carbon double bond
• 1
• 1
• No
• Monomer without the double bond and with bonds on
  either side
• A few, long chains
• Possible

Step-by-step reactions Noindependent
events No Has reacting bifunctional groups on
the ends 2 2 (usually) Yes (usually) Two
monomers joined together Many not very long
chains Unlikely
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Rearrangement Polymerization
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Thank You

• Remember the molecules