Statics and dynamics of poly(ethylene glycol)-stabilized colloids

Condensed Matter lunchtime seminar

Statics and dynamics of poly(ethylene glycol)-stabilized colloids

  • Event time: 1:00pm
  • Event date: 8th November 2004
  • Speaker: Johan Bergenholtz (University of Gothenburg Sweden)
  • Location: Room 2511,

Event details

Steric stabilization is an effective means to achieve colloidal stability at rest and under shear. However, marginal solvent conditions produce short-range colloidal attractions, leading to aggregation at rest and complex behavior under flow. In this project we chart the statics and dynamics of aqueous dispersions of polystyrene spheres, stabilized by grafted poly(ethylene glycol) (PEG) as functions of concentration and solvent quality. Dynamic (3D) light scattering and linear viscoelastic rheology measurements under good solvent conditions reveal glass-like behavior on increasing particle concentration. Addition of Na2CO3 and raising the temperature leads to reversible aggregation. Preliminary SANS measurements, using contrast matching to focus on the structural changes in the PEG layer, will be reported, as well as the structural evolution on approaching and crossing into the aggregation regime.

This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..

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