Polyglycols at Clay Surfaces
Nick Green (previous student, left the group in 1997)
System under investigation
Aqueous, dilute dispersions of clay colloids in the presence of water-soluble nonionic polymers.
Why study this system?
The addition of polymers to clay particles is a technically important and extremely powerful method of controlling the stability of clay dispersions. The adsorption of non-ionic polymers on clays has not been studied to the same degree as polyelectrolytes. The addition of non-ionic polymers to a concentrated clay suspension causes a dramatic reduction to the swelling of the clay in the presence of water. However, this mechanism is not fully understood.
Aim of the project
- Investigate the interactions of non-ionic polymers and clays
- Use model clay colloids, laponite and montmorillonite
- Determine polymer conformation at the clay interface
- Study effect of polymer properties on adsorption
Techniques Utilised
- Nuclear Magnetic Resonance (NMR)
- Small-Angle Neutron Scattering (SANS)
Nuclear Magnetic Resonance Studies
The technique of 1H NMR solvent relaxation [1] has been used to probe the effect of the adsorption of poly(ethylene glycol) at the clay-water interface. Montmorillonite and laponite surfaces have been studied and the nature of the surface has been shown to have a considerable effect on the nature of the adsorption.
Small-Angle Neutron Scattering Investigations
SANS has been used to study the conformation of the adsorbed poly(ethylene glycol) layer on discrete laponite particles [2]. The polymer adopts a very flat conformation on the clay surface.
References
- G.van der Beek, M.A.Cohen Stuart, T.Cosgrove, Langmuir, 1991, 7, 327
- N.Green, T.Cosgrove, Report on Experiment RB 7262 at Rutherford Appleton Laboratories, Didcot, England
Acknowledgements
This project is funded by the EPSRC and Schlumberger Cambridge Research
