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Polymer/Surfactant/Surface Interactions


Robin Wesley

Robin Wesley (previous student, left the group in 1999)

This project aims to study the adsorption of polymers, particularly polyelectrolytes, onto surfaces in the presence of a surfactant. These systems will act as models for particle deposition in a variety of commercially available products such as detergents and personal care formulations.

Techniques to be used include Small Angle Neutron Scattering (SANS), Nuclear Magnetic Resonance (NMR) and Photon Correlation Spectroscopy (PCS).

At present I am using grafted and star polymers as simplified systems, these hold an advantage over physically adsorbed polymer layers in that the surfactant molecules cannot displace polymer from the solid/ liquid interface.

Particles
Schematic of Systems Studied: Polymer Coated Particles.

Experiments with physically adsorbed layers of Poly(ethylene glycol), PEG in the presence of the surfactant sodium dodecyl sulphate, SDS have shown that around the critical micelle concentration of the surfactant the adsorbed polymer layer becomes much thinner. At higher surfactant concentrations the layer increases in thickness again. By studying the systems described above it should become clear whether the decrease in thickness of the layer is caused by a collapse of the polymer onto the surface without any desorption of polymer, or by the small surfactant molecules being adsorbed preferentially at the solid liquid interface causing the polymer to be displaced.

This project is funded by the EPRSC and Unilever