title: Depletion stabilization in nanoparticle-polymer suspensions: multi-length-scale analysis of microstructure.
abstract: We study the mechanism of depletion stabilization and the resultant microstructure of aqueous suspensions of nanosized silica and poly(vinyl alcohol) (PVA). Rheology, small-angle light scattering (SALS), and small-angle X-ray scattering (SAXS) techniques enable us to analyze the microstructure at broad length scale from single particle size to the size of a cluster of aggregated particles. As PVA concentration increases, the microstructure evolves from bridging flocculation, steric stabilization, depletion flocculation to depletion stabilization. To our surprise, when depletion stabilization occurs, the suspension shows the stabilization at the cluster length scale, while maintaining fractal aggregates at the particle length scale. This sharply contrasts previously reported studies on the depletion stabilization of microsized particle and polymer suspensions, which exhibits the stabilization at the particle length scale. On the basis of the evaluation of depletion interaction, we propose that the depletion energy barrier exists between clusters rather than particles due to the comparable size of silica particle and the radius gyration of PVA.
authors.affiliation: Department of Chemical Engineering, KU Leuven, University of Leuven , W. de Croylaan 46, B-3001 Heverlee, Belgium.
authors.forename: Sunhyung
authors.initials: S
authors.lastname: Kim
authors.forename: Kyu
authors.initials: K
authors.lastname: Hyun
authors.forename: Joo Yong
authors.initials: JY
authors.lastname: Moon
authors.forename: Christian
authors.initials: C
authors.lastname: Clasen
authors.forename: Kyung Hyun
authors.initials: KH
authors.lastname: Ahn
mesh_terms: D005427:Flocculation; D008958:Models, Molecular; D008968:Molecular Conformation; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011142:Polyvinyl Alcohol / Q000737:chemistry*; D012212:Rheology; D013535:Suspensions
chemical_list: D013535:Suspensions; D011142:Polyvinyl Alcohol