Graduate Seminar: Tuning Viscosity Through Packing of Soft Colloidal Particles: From Flow to Gel Formation

Event Details

  • Speaker(s): Hurmiz Shamana
  • Date:
  • Time: 12:45 PM
  • Location: MacN 415

Abstract

Phytoglycogen is a natural, highly branched polysaccharide nanoparticle extracted and purified from sweet corn. The nanoparticles possess many unusual properties that suggest a broad range of applications in cosmetics, food and nutrition, and biomedicine. These applications stem from a strong interaction between the nanoparticles and water, which has motivated our studies of aqueous phytoglycogen dispersions. We study these dispersions using rheology, a powerful experimental technique in which a well-defined shear is applied to a material, allowing the measurement of mechanical properties such as the zero-shear viscosity. Unlike other polysaccharides such as starch, we find that the zero-shear viscosity of phytoglycogen dispersions remains very low over an extended range of concentrations C, increasing significantly only for C ≥ 20% w/w. Converting these concentrations to volume fractions suggests that C = 20% is the point at which the particles begin to touch. This implies that the particles do not interact significantly until they are forced into contact at very high concentrations, accompanied by large increases in viscosity as the colloidal particles form a gel.

Further Details

Snacks will be provided at 12:30 pm. The talk will begin at 12:45. Make sure to follow the Graduate Seminar Series on Facebook.