Phil Attard School of Chemistry, University of Sydney Forces and Interactions between Soft Particles Wednesday 11th, August 14:05-14:55pm, Carslaw Lecture Theatre 273. The surface forces that occur between colloidal particles control their interactions and adhesion. Traditional theories have focused upon rigid particles but increasingly it has become apparent that deformation can be important, particularly for soft materials. In this talk methods to treat elastic, viscoelastic, and fluid particles are discussed. The challenge is to describe the deformation of the surfaces, and the forces causing that deformation self-consistently. The problem is cast in the form of an integral equation that is solved by iteration. Several approximate and asymptotic results are also derived. For the viscoelastic problem a time-dependent Young's modulus is invoked and it is shown that the model is capable of a quantitative description of experimental data. An analytic theory is also developed for the interactions of particles with bubbles or droplets and again agreement with experiment is secured.