CoII Mediated Catalytic Chain Transfer Polymerisation

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Co(II) Mediated Catalytic Chain Transfer
Polymerisation

• D M Haddleton
• S N Richards
• UMIST RSC Annual Meeting April 2000

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Control of Macro-Molecular Structure
Molecular weight Chain Architecture
Functionality Rate/Exotherm
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Recent Innovations to Control FRP

• Reversible homolytic cleavage
• Nitroxide-Mediated LRP (CSIRO, Georges, Fukuda,
  Hawker,...)
• Transition Metal Mediated LRP (ODriscoll,
  Wayland, Sawamoto, Matyjaszewski, Percec,
  Haddleton,...)
• Chain transfer processes
• Addition Fragmentation (CSIRO)
• RAFT (CSIRO)
• Catalytic Chain Transfer Polymerisation (Smirnov,
  Gridnev, Hawthorne, Janowicz, CSIRO, Haddleton,
  Davis,...)
• Combination of both
• Iniferters (Otsu)

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Catalytic Chain Transfer Polymerisation (CCTP)

• Certain Low-Spin Cobalt Complexes
• Typical Mon/Co ratio of ca. 106

CoBF
CCTP of MMA using CoBF at 60oC
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Catalytic Chain Transfer Polymerisation
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CCT Emulsion Polymerisation of MMA

• MMA/H2O 200/450 mL/mL
• CoBF in MMA 0.00, 14.53, 16.56
• 18.59, 25.03, 35.75 ppm
• AOT-100 (2g) ACVA (2g) T80 oC

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CCT Emulsion Polymerisation of MMA with ab initio
Monomer Shot Addition of 20

• CoBF 35.75, 14.53, 17.87, 10.37 ppm

PDIs ca. 2.0 CSE 1300 CSE(partitioning) 6000
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CCT Emulsion Polymerisation of MMA with various
Cobal(II)oximes
Catalyst structure CS(bulk) CoMMA/Coaq CSE
40,000 0.69 1300 12,300 8.09
2233 14,000 99.0 3500

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CCT Emulsion Copolymerisation of MMA

• Monomer 2 ratio M1/M2 CSE mon. shot
• BMA 50/50 700 yes
• BMA 0/100 600 no
• HEMA 70/30 1300 yes
• MAA 90/10 1250 -
• 70/30 200-600 -

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Industrial Interest of CCTP

• Catalytic Chain Transfer Polymerisation is
  commercially exploited
• A number of companies are active in exploring
  application to specific products
• Almost like an open secret with only a few people
  in-the-know which somehow has not captured the
  academic imagination
• Catalyst are relatively easy to synthesise and
  easy to exploit

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Near Diffusion Controlled Reactions

• A fast reaction is composed of two events in
  series
• Diffusion of reagents to undergo successful
  encounter
• Intrinsic chemical reaction
• Overall rate coefficient, k, is expressed as
• For small molecules

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Determination of Chain Transfer Constants

• Classical Mayo Method
• Chain Length Dependent Method

In which L is slope of linear fit on the high
molar mass part of ln(n(DP)) with significant
signal intensity
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Diffusion Ordered 2D-NMR Spectroscopy
(DOSY)

• FT pulsed field gradient method
• LED pulse sequence

t
d
de
Te
T
Gi
p/2
p/2
p/2
p/2
D
Gibbs, S. J. Johnson, C. S., Jr. J. Magn.
Reson., 1991, 93, 395
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I/I0 vs. Gi
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Diffusion Coefficients
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Magnetic Properties of Co(II) complexes using
SQUID

• Magnetisation M vs. T in different applied
  fields, H.
• Calculate magnetic susceptibility c
• Curie law
• fit 1/c vs. T gives information on
• diamagnetic contributions from ligands, c0
• interactions between molecules, q
• the meff indicating spin state

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Raw SQUID Data
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M/H vs. T at Various Applied Fields
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Curie Law Fit
c0 3.4318 10-5 emu mol-1 C 0.3945 emu
mol-1 K-1 q 0.287 K meff 1.77 mB
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Acknowledgments

• Warwick Polymer Group Avecia
• Stefan Bon John ODonnell
• Kevin Suddaby Steve Yeates
• Darren Maloney John Padget
• Jennifer Waterson
• David Morsley
• Tim Horne
• Martin Lees
• Tom Davies (UNSW ) Funding
• Avecia, EPSRC