FAIR-CT98-5014 Development of starch-based nanoparticles: structure, colloidal and rheological properties

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FAIR Area 1.2 - Green Chemicals and Polymers Chain : FAIR Marie Curie Research Training Grants : Nanotechnology : Pharmaceuticals/Cosmetics

Objectives:

In a previous study, it was found that surface charges could contribute largely to the rheological behaviour of starch-based particles (cross-linked with epichlorohydrine) in salt-free aqueous suspensions. Further research continued with performing rheological experiments on dilute and semi-dilute suspensions, and varying the ionic strength, the cross-linking degree of the particles, and the type of the cross-linking agent (using trisodium trimetaphosphate). Supplemental experiments have been also performed on charged, rigid silica spheres in order to establish a parallel between the rheological behaviour of particles with a well-defined structure and starch-based hydrogens.

Activities and results:

It has been found that starch-based particles behave like polyelectrolytes in aqueous suspensions, most likely due to the dissociation of hydroxyl groups carried on the glucose units. Charged rigid spheres also produce the polyelectrolyte effect (decrease of the reduced viscosity versus the particle concentration) at very dilute regimes.

Conclusions:

Two important conclusions can thus be put forward:

1. on one hand, the polyelectrolyte effect is a one-particle problem, involving only the number density of surface charges contributing to the Debye length and thereby the effective volume of the particles
2. on the other hand, the polyelectrolyte effect is a generic phenomenon characterising charged particles in suspensions.

Keywords: starch, nanoparticles

Contacts

Scientific Supervisor

• Jeroen VAN SOEST / A&F BV NETHERLANDS