POLYMER-INDUCED FORCES BETWEEN COLLOIDAL PARTICLES - A MONTE-CARLO SIMULATION

Monte Carlo simulations of the fluctuating bond lattice model are used to determine the force between colloidal particles immersed in a nona dsorbing polymeric fluid. Monodisperse systems with chain lengths of 2 0 to 100 segments are studied at occupation fractions ranging from 0.1 to 0.6, covering the semidilute and dense regimes. The variation of t he force with concentration, particle diameter, and interparticle sepa ration is in qualitative agreement with predictions of scaling theory and of integral equations for the colloid-polymer system. In semidilut e solutions the force is purely attractive and displays an approximate ly linear dependence upon separation for small colloid separations. At higher concentrations the force is repulsive, for certain separations .