Preparation and Properties of Starch-Based Colloidal Microgels

✍ Scribed by Yannick Dziechciarek; Jeroen J.G. van Soest; Albert P. Philipse

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 372 KB
• Volume: 246
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.2001.8044

✦ Synopsis

Novel starch microgels were prepared by emulsion cross-linking and characterized with respect to shape, volume, and mass density. Starch microgels appear to be negatively charged ( approximately -50 mV), with a particle size varying as a function of the type of cross-linker (ca. 0.25-10 microm). Environmental scanning electron microscopy observations show a dependence of the particle swelling on the cross-linking density. Viscosimetry reveals that starch microgels behave as charged polymers, where the reduced viscosity increases with dilution (anomalous viscosity behavior) for sufficiently low kappaalpha (ca. kappaalpha <3), the ratio of the particle radius (a), and the Debye length (kappa(-1)). Analogous results are obtained for reference-charged rigid silica spheres, which approach the hard sphere limit for increasing ionic strengths. The shape of the microgels appears to play a minor role in the anomalous viscosity behavior, which is more likely dominated by electrostatic effects.