Volume 82, Number 6, June 2008
Article Number 68002
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 29 May 2008
EPL, 82 (2008) 68002
DOI: 10.1209/0295-5075/82/68002

Phase diagram for a mixture of colloids and polymers with equal size

R. Tuinier1, P. A. Smith2, W. C. K. Poon2, S. U. Egelhaaf2, 3, D. G. A. L. Aarts4, H. N. W. Lekkerkerker5 and G. J. Fleer6

1  Forschungszentrum Jülich, Institut für Festkörperforschung - D-52425 Jülich, Germany
2  SUPA and School of Physics, The University of Edinburgh, Edinburgh - EH9 3JZ, UK
3  Condensed Matter Physics Laboratory, Heinrich-Heine-University - Universitätsstrasse 1, D-40225 Düsseldorf, Germany
4  Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford South Parks Road, Oxford OX1 3QZ, UK
5  Van't Hoff Laboratory, Utrecht University - Padualaan 8, 3584 CH Utrecht, The Netherlands
6  Laboratory of Physical Chemistry and Colloid Science, Wageningen University - 6703 HB Wageningen, The Netherlands

received 29 February 2008; accepted in final form 21 April 2008; published June 2008
published online 29 May 2008

We present the phase diagram of a colloid-polymer mixture in which the radius a of the colloidal spheres is approximately the same as the radius R of a polymer coil (q = R/a$ \approx$ 1). A three-phase coexistence region is experimentally observed, previously only reported for colloid-polymer mixtures with smaller polymer chains (q $\lesssim$ 0.6). A recently developed generalized free-volume theory (GFVT) for mixtures of hard spheres and non-adsorbing excluded-volume polymer chains gives a quantitative description of the phase diagram. Monte Carlo simulations also agree well with experiment.

82.70.Dd - Colloids.
64.60.-i - General studies of phase transitions.
61.25.H- - Macromolecular and polymers solutions; polymer melts.

© EPLA 2008