ATRP Polymerised

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• ATRP Polymerised
• Peg-methylether methacrylate-Montmorillonite
  Nanocomposites
• Dr.A.Bowden
• The University of Durham

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Nanocomposites
Nanocomposite - one or more dimensions of the
materials structure exist at nano level.
nm
Clay
Monomer/polymer
nm
nm
Exfoliated No d-spacing
Intercalated Increased d-spacing
Conventional Composite
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• Nanocomposite Benefits/Uses
• Enhanced properties at low clay loadings compared
  to conventional clay/polymer mixtures.
• Barrier properties gases and liquids.
• Thermal stability, flame resistance.
• Stiffness
• Clarity
• More Easily Recycled
• Uses Car parts, packaging.

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Overview - Our Research

• Functionalised short chain polyethylene and
  propylene oxides.
• Water soluble add to unmodified water-suspended
  clay.
• Variety of clays/cation exchanged clays.
• Diversity Discovery Prepared large number of
  samples.
• Interested in formation of intercalated
  composites rather than exfoliated
• Clay catalysed reactions.
• Materials/Modelling collaborations.
• J. Mat. Chem. 2003, 13, 2540

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Clays

• Smectite clays Montmorillonite.

• 2 Tetrahedral (silica)
• 1 Octahedral (M(OH))6.
• Swellable Alkali metal ions between layers.
• High cation exchange capacity.
• Large effective surface area for absorption.

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Atom Transfer Radical Polymerisation (ATRP)
Mechanism

• Can be done in water
• Fast, good control over polydispersity

Wang, J. S., Matyjaszewski, K., J. Am. Chem.
Soc., 1995, 117, 5614 Sawamoto, M., Kamigaaito,
M., Trends Polym. Sci., 1996, 4, 371 Wang, X.-S.,
Armes S.P., Macromolecules, 2000, 33, 6640.
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Reagents
Solid, but pH adjustment.
Peg-methylether methacrylate Mw 300 g/mol n
4-5 Mw 2,060 g/mol n 44-45
Catalyst Cu(I)Cl bipyridine
Not soluble in water, but soluble in monomer
Initiators
Monomers
Catalyst
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ATRP Procedure

• Add the monomer and initiator to water.
• Perform one freeze pump/thaw/cycle.
• Add solid catalyst components
• Solution stirred under argon.
• Monitor by NMR.
• Colour change from brown to green (blue
  failure).
• Removal of water.
• Removal of catalyst.

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NMR Spectra

• Easy to monitor polymerisation
• Alkene peak disappears
• New peak for acrylate polymer backbone.

Monomer
ATRP 1500
ATRP 150
ATRP 1200
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GPC Data
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Composite Preparation

• 1) Pre-made polymer
• Polymer prepared by ATRP method.
• Suspend clay, add polymer.
• Monitor intercalation (XRD).
• Oven dry.
• 2) In-situ
• Suspend clay, add monomer
• Add initiator then catalyst.
• Monitor reaction (FT-IR).
• Oven dry.

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ATRP Results XRD/FT-IR
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XRD Spectra
150,000 M.Wt.
15,000 M. Wt.
Pre-made In-situ
Scan 2? 2½-15o, step 0.020o
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Layers

• Expansion 0.4 nm per layer

2.2 nm
1.8 nm
1.4 nm
1.0 nm
Trilayer???
Monolayer
Bilayer
No intercalant
2.2 nm
2.2 nm
Ref M. Lerner, J. Wu Chem. Mat., 1993, 5, 835
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Simulation

• Na-Montmorillonite- polyethylene glycol. 
• 20,000 atom supercells after 1ns of molecular
  dynamics (MD) simulation.

Colour  Al light green, Mg pink, O red, C
grey, H white, Si Orange, Na light brown
(in Na-Mmt only, K purple.
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Simulations II - Trilayers

• K-Montmorillonite
• Polyethylene glycol composite
• 20,000 atom supercells after 1ns of
• molecular dynamics (MD) simulation.

• Na-Montmorillonite poly(ethylene oxide)
  methylether acrylate
• 1000 atom composite after 50ps of MD simulation. 

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• FT-IR spectra
• Useful for acrylates CO stretch.
• Typically shifted by 10 20 cm-1 unsaturated
  to saturated ester.
• In-situ identical to pre-made.

Pre-made In-situ
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TGA data In-Situ vs. Prepared

• In-situ shows differences, likely due to
  incomplete polymerisation.

Pre-made In-situ
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Conclusions

• There are differences between in-situ
  polymerisation
• and pre-making then intercalating.
• Degree of polymerisation/control lower.
• TGA, FT-IR.
• XRD exfoliation at larger d-spacing.
• Compare to polymerisation of peg-diacrylate with
  benzoyl peroxide.

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Acknowledgements

• Dr. A. Whiting
• Prof. P. Coveney, Dr. P. Boulet, Dr. H. Greenwell
  Computational
• Prof. J. Evans, B. Chen Materials
• EPSRC - Money