Recent advances in self-healing polymer composites

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Recent advances in self-healing polymer composites

• Michael R. Kessler
• NIST Visit
• Jan. 26, 2012

Co-author Timothy C. Mauldin
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Outline

• Self-Healing Polymers
• The healing monomer a critical design
  parameter
• Choosing adequate healing monomers
• Bulk Polymerization Kinetics
• Catalyst Dissolution Kinetics
• New methods of testing healing monomers
• Conclusion

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Solubility Parameters

• Hildebrand Solubility Parameter, d, developed to
  measure strength of the aggregrate intermolecular
  forces of a chemical, normalized by its molar
  volume
• d2 E/V
• E cohesive energy, V molar volume
• Hansen elaborated by separating the Hildebrand
  parameter into three specific types of
  intermolecular forces Dispersion (dD), Dipole
  (dP), and Hydrogen bonding forces (dH).
• d2 dD2 dP2 dH2
• E/V ED/V EP/V EH/V
• Solids and liquids with similar parameters are
  expected to be chemically compatible, and
  therefore faster dissolution kinetics.

C.M. Hansen Hansen Solubility Parameters A
Users Handbook, 2nd ed. CRC Press Boca Raton,
FL, 2007.
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Solubility Parameters

• A 3-dimensional Solubility Map can be constructed
  with each parameter on an axis (often the dD
  axis is omitted, giving a 2-dimensional plot)

• A sphere is drawn around the liquids in which a
  solid dissolves
• The center coordinates are the parameters of the
  solid

An example of the solubility map
C.M. Hansen Hansen Solubility Parameters A
Users Handbook, 2nd ed. CRC Press Boca Raton,
FL, 2007.
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Catalyst Parameters

• Grubbs Catalysts parameters determined by
  measuring dissolution rate/solubility in liquids
  with well-defined parameters.

C.M. Hansen Hansen Solubility Parameters A
Users Handbook, 2nd ed. CRC Press Boca Raton,
FL, 2007.
6
Catalyst Parameters

• Grubbs catalyst shown to have two dissolution
  spheres whose center coordinates are roughly (dP
  2.9, dH 3.3) and (dP 7.0, dH 7.1).
• Literature precedent exists for organometallic
  compounds having two solubility spheres.

C.M. Hansen Hansen Solubility Parameters A
Users Handbook, 2nd ed. CRC Press Boca Raton,
FL, 2007. Mauldin, T.C. and Kessler, M.R. J.
Mater. Chem. 2010, 20, 4198-4206.
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Healing Monomer Map

• Smalls Method
• dx2 SGx/V
• dx solubility parameter of an x-type of
  cohesive force
• SGx additive group contributions of an x-type
  cohesive force
• V molar volume

Group GD
CH3 438
CH2 272
gtCH 57
gtCCH 266
Phenyl 1504
O (ether) 143
CO (ketone) 563
COO (ester) 634
CN 839
Mauldin, T.C. and Kessler, M.R. J. Mater. Chem.
2010, 20, 4198-4206.
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Healing Monomer Map

• No healing monomers parameters coincide very
  well with catalysts parameters.
• Simple rule-of-mixing states that any miscible
  blend of liquids takes on the parameters
  intermediate between the individual liquids
• dx,blend S?i dx,i
• dx,blend parameter of an x-type cohesive force
  in a blend.
• ?i volume fraction of the i-th solvent in the
  blend.
• dx,i parameter of an x-type cohesive force of
  the i-th solvent in the blend.

Catalysts parameters
Mauldin, T.C. and Kessler, M.R. J. Mater. Chem.
2010, 20, 4198-4206.
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Model Validation


Entry Volume Fraction Volume Fraction Volume Fraction dP dH
Entry R H R C(O)CH3 R COOEt dP dH
1 1 0 0 1.4 3.7
2 0 1 0 3.2 6.5
3 0 0 1 5.7 6.0
4 .62 .32 .06 2.9 3.3
Melting Point 45 C, testing at 50 C
Matches catalysts parameters

• Amount dissolved determined by 1H-NMR (relative
  intensity catalyst/internal standard).
• Healing monomer blend chosen to match catalysts
  parameters.

Louie, J. and Grubbs, R.H. Organometallics,
2002, 21, 2153-2164.
Mauldin, T.C. and Kessler, M.R. J. Mater. Chem.
2010, 20, 4198-4206.
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Model Validation

Entry Volume Fraction Volume Fraction Volume Fraction dP dH
Entry R COOH R CHO R CH2Br dP dH
1 1 0 0 3.5 10.3
2 0 1 0 10.4 6.9
3 0 0 1 6.2 5.0
4 0.27 0.36 0.37 7.0 7.1
Matches catalysts parameters

• Amount dissolved determined by 1H-NMR (relative
  intensity catalyst/internal standard).
• Healing monomer blend chosen to match catalysts
  parameters.

Mauldin, T.C. and Kessler, M.R. J. Mater. Chem.
2010, 20, 4198-4206.
11
Questions?
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Calculation of norbornenes parameters

• d2 E/V (?HV RT)/V
• E cohesive energy
• V molar volume
• ?HV heat of vaporization
• T temperature
• R Ideal gas constant
• dD2 dhmorph2 Ehmorph/Vhmorph (?HV,hmorph
  RT)/V
• - Variables same as above
• dP2 37.4(DM)/V
• DM dipole moment
• V molar volume
• dH2 d2 - dD2 - dP2

Norbornene
Norbornane (norbornenes hmorph)
Mauldin, T.C. and Kessler, M.R. J. Mater. Chem.
2010, 20, 4198-4206.