Depletion and cluster formation in soft colloid - polymer mixtures

¹ Institute of Electronic Structure and Laser-FORTH - Heraklion, Crete, Greece
² Department of Chemistry, University of Crete - Heraklion, Greece
³ Department of Materials Science and Technology, University of Crete Heraklion, Greece
⁴ Institut für Theoretische Physik II, Heinrich-Heine Universität Düsseldorf Düsseldorf, Germany
⁵ Department of Chemistry, University of Athens - Athens, Greece
⁶ NRC, Institute of National Chemical Process and Enviromental Technology Ottawa, Ontario Canada

Received: 18 May 2005
Accepted: 19 September 2005

Abstract

The dynamics of colloidal star —linear homopolymer mixtures is investigated by photon correlation spectroscopy. In dilute star solutions, osmotic forces due to the added polymers lead initially to a shrinkage of the stars and eventually, at higher polymer concentrations, to stable star clusters. Furthermore, concentrated glassy star solutions melt upon addition of small amounts of linear polymers, as manifested by the remarkable speed-up of the star self-diffusion. Quantitative description of the experimental findings is provided by calculations of the effective star-star pair potential.