Eur. Phys. J. E (2009) 28: 165-171
https://doi.org/10.1140/epje/i2008-10387-2

Regular Article

Temperature-sensitive poly(N-Isopropyl-Acrylamide) microgel particles: A light scattering study

¹ Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, CH-1700, Fribourg, Switzerland
² Adolphe Merkle Institute, University of Fribourg, CH-1700, Fribourg, Switzerland
³ School of Chemistry and Chemical Biology, University College Dublin, Dublin, Belfield, Ireland

^* e-mail: Frank.Scheffold@unifr.ch

Received: 11 August 2008
Published online: 25 November 2008

Abstract

We present a light scattering study of aqueous suspensions of microgel particles consisting of poly(N-Isopropyl-Acrylamide) cross-linked gels. The solvent quality for the particles depends on temperature and thus allows tuning of the particle size. The particle synthesis parameters are chosen such that the resulting high surface charge of the particles prevents aggregation even in the maximally collapsed state. We present results on static and dynamic light scattering (SLS/DLS) for a highly diluted sample and for diffuse optical transmission on a more concentrated system. In the maximally collapsed state the scattering properties are well described by Mie theory for homogenous hard spheres. Upon swelling we find that a radially inhomogeneous density profile develops.