ON THE CONFORMATION OF NONADSORBING POLYMERS IN COLLOIDAL SUSPENSIONS

This paper investigates the interaction of dilute polymer solution wit h a colloidal suspensions. The object of consideration is the effectiv e monomer-monomer potential between different polymer pieces. Unlike i n the current polymer Literature the effective potential is calculated beyond the pseudo potential approximation, i.e., detailed effects of the colloidal liquid is taken into account. It is shown that the effec tive potential can be used to discuss the stability of the three compo nent system, polymer chains, good solvent, and colloidal particles. Th e latter are approximated as hard spheres. Two regimes are found: The polymer chains are collapsed (as a function of the packing fraction of the colloids), if the size of the polymer is much larger compared to the colloids. This corresponds to the unstable regime. If the polymer chains are smaller, it is shown that the depletion effect dominates th e physical behavior and the solution is stable. Detailed criteria are worked out in the form of an eigenvalue equation for the interactions and conformations. (C) 1997 American Institute of Physics.