8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.181Thermophysical properties of thermosensitive microgelparticlesSimon Wongsuwarn, 1 Daniele Vigolo, 2 Roberto Cerbino, 3 Roberto Piazza, 2Andrew Howe, 4 Alberto Vailati, 5 and Pietro Cicuta 61 University of Cambridge, BSS Cavendish Laboratory, JJ Thomson Avenue CB39BB,Cambridge, United Kingdom2 Politecnico di Milano, Milano, Italy3 Universita degli Studi di Milano, Segrate, Italy4 Schlumberger Cambridge Research, Cambridge, United Kingdom5 Universita degli Studi di Milano, Milano, Italy6 University of Cambridge, Cambridge, United KingdomPoly(N-isopropylacrylamide) (PNIPAM) microgel particles are colloidal gel particles that swellin good solvency conditions [1]. We present the characterisation of a variety of thermophysicalproperties of PNIPAM microgel dispersions near the volume phase transition temperature (VPTT).These include individual particle characteristics (size and thermophoretic mobility) as well asbulk dispersion characteristics (rheology, refractive index and heat capacity). Thermophoresisrefers to the motion of colloids induced by thermal gradients [2]. The thermophoretic behaviorof a PNIPAM microgel dispersion is investigated using dynamic light scattering (DLS) and beamdefection (BD). We show for the first time the temperature dependence of the Soret coeffcient ofPNIPAM microgels near the VPTT. Our results suggest that the dominant effect on thermophoreticbehavior lies in the role of the polymer-solvent interaction.[1] A. Howe, S. Desrousseaux, L. S. Lunel, J. Tavacoli, H. N. Yow, A. F. Routh Advancesin Colloid and Interface Science (2009)[2] R. Piazza, Soft Matter, 1740-1744 (2008)181