Preparation and Analysis of Polyalkylene oxideClay Nanocomposites

1
Preparation and Analysis of Poly(alkylene
oxide)-Clay Nanocomposites

• Dr. A. Bowden
• University of Durham

2
Nanocomposites

• Nanocomposite - one or more dimensions of the
  materials structure exist at nano level.

Clay
Intercalant
Intercalated
Exfoliated
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Nanocomposite Benefits

• Enhanced properties at low clay loadings compared
  to clay/polymer mixtures.
• Barrier properties gases and liquids.
• Thermal stability, flame resistance.
• Stiffness
• Clarity
• More Easily Recycled

4
Industrial Applications of Nanocomposites

• Automobile industry - Late 1980s Toyota
  montmorillonite - nylon
• GMC/Chevrolet polyolefin - montmorillonite
• Packaging Bayer Durethan - replacement for
  EVOH good barrier/increased stiffness, good
  clarity
• Honeywell - Aegis Film/paper coating, beer
  bottles, engineering applications.
• Nanocor 7 million pounds Nanomer production
  capability to increase to 100 million

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Our Research

• Use of wide range of functionalised short chain
  polyethylene and propylene oxides.
• Number of repeat units 2-9
• Water soluble.
• End groups acrylates, alcohol, aldehyde, amine,
  glycidyl.
• Variety of clay/cation exchanged clay.
• Clay catalysed reactions.

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Clays

• Smectite clays Montmorillonite and hectorite.

2 Tetrahedral (silica) 1 Octahedral
(M(OH))6. Swellable Alkali metal ions between
layers. Cation exchange capacity. Large
effective surface area for absorption.
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Literature Poly(alkylene oxide) Studies

• Almost all polyethylene oxide-montmorillonite.1
• Electrochemical devices - Solid state battery
  applications.
• Computer Modelling Lithium dynamics.2
• One example polyethylene and propylene oxide
  diamine montmorillonite.3

• 1. Chem. Mater., 1992, 4, 1395-1403. 4. Chem.
  Mater., 2002, 14, 2171-2175. 5. Macromolecules,
  2001, 34, 8832-8834.

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Preparation of Samples

• Goal - Prepare large numbers of samples on scale
  sufficient for subsequent analysis.
• Ability to vary monomer(s).
• Analyses - Check for intercalation by XRD.
• Chemical changes by IR/NMR.
• Amount of intercalated monomer by TGA.

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Preparation of Samples
300-400 mg Clay
Dry in Oven
Add monomer
Wash And Grind
Stir and sonicate
Sonicate
XRD
TGA
IR
Analysis
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Monomers
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Preparation of Modified Poly(alkylene oxides)

• Aldehyde.
• Swern oxidation of alcohol (DMSO, oxalyl
  chloride)

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Diamine Preparation

• Amine prepared via tosylate.

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Analysis of Samples

• Solid state FT-IR - KBr disc.
• X-ray powder diffraction - d spacing.
• Thermal gravimetric analysis
• water/organic content.
• Solid state 13C NMR.

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X-Ray Diffraction

• Scan from 2.5 15 ?.
• Pristine clay montmorillonite 12 Å.
• Intercalated monomer causes gallery expansion.
• In most cases to 16-18 Å.
• Exceptions aldehyde/amine end groups.
• Shorter d-spacings 13-14 Å.

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XRD Data Montmorilloniteand Hectorite
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Mono Versus Bilayer
17.6 Å
13.6 Å
9.6 Å

• Expansion 4 Å per layer.
• Polypropylene oxide diamine, polyethylene oxide
  diamine always form monolayer.
• Polyethylene oxide dialdehyde - monolayer
• Polyethylene oxide can form either a mono or
  bilayer.
• gt30 wt monomer XRD - 17 Å.
• 10 wt monomer XRD - 14 Å.

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FT-IR Analysis

• Useful for acrylates CO stretch. Typically
  shifted by 10 20 cm-1 unsaturated to
  saturated ester.
• Diamines large shift N-H bend of amine (1591
  cm-1), shifted by 60-70 cm-1.
• Polyethylene oxide - dicarboxylic acid mixtures
  carboxylic ester formation.

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IR Data Montmorilloniteand Hectorite
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Reaction with Acids

• Polyethylene oxide and polypropylene oxide with
  dicarboxylic acids.
• Formation of ester depends on clay and acid.
• Montmorillonite phthalic and maleic acids.
• Acid and montmorillonite no intercalation.
• Hectorite - no reaction with any acid tested.

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XRD/IR Data Dicarboxylic Mixtures
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Solid-State NMR

• Only get useful results with hectorite.
• Montmorillonites high iron content leads to line
  broadening.
• Acrylates additional alkyl peak reduced alkene
  peak.
• Polypropylene glycol diamine no major changes to
  original except broadening.

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Thermal Analysis

• TGA water/organic content
• Room temperature 600oC.
• Bilayers typically 20-30 wt organic content.
• Monolayer (-diamine, -dialdehyde) 10-15 wt.
• Water content less than 2.

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Monomer/Polymer Recovery

• Literature LiCl works for various
  nanocomposites polystyrene, polyacrylonitrile,
  polyamide.
• LiCl didnt work at room temperature with any of
  our nanocomposites.
• TGA showed most of the organic material still
  present.
• At reflux recovered organic material but had
  decomposed.

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Conclusions

• Can intercalate a wide range of functionalised
  poly(alkylene oxides) in montmorillonite and
  hectorite.
• Reactions occur that dont in the absence of clay
  
• i) Polyethylene and propylene oxide with acids
• ii) Polymerisation of inhibited acrylates
• Diamine strong interactions/reaction with clay.
• Cant recover monomer/polymer intact using ion
  exchange.

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Acknowledgements

• Dr. Andy Whiting
• Dr. Dave Apperley Solid-state NMR
• Prof. P. Coveney, Dr. P. Boulet Computational
• Prof. J. Evans, B. Chen Materials
• EPSRC - Money