Abstract

Our characterisation and understanding of the physical properties of many complex liquids, such as colloids and polymers has improved in recent years. One aspect of these systems that distinguishes them from small molecules is the nature of the interparticle interaction. The interaction can range from being extremely hard to being extremely soft. In this talk I will focus on the effects of softness on the physical properties of these meso-particulate systems. This includes the thermodynamic, structural and transport behaviour. The results are partly from theory and partly from molecular dynamics simulation of a model soft particle fluid, using a generalised soft-sphere potential φ(r)=ε(σ/r)n, where the exponent, n is a variable which can be used to tune the softness of the particles. Model liquids with n ranging from 4 to 1152 were chosen to cover the transition, respectively, from very soft (i.e. polymer-like) to very stiff (i.e., large colloid) particles. Statistical mechanical theory and Molecular Dynamics simulations have been used to help provide an understanding and the first steps towards a theoretical description of these systems. Results of this on-going work also include the viscosity and shear stress relaxation function, and elastic constants.