Phase stability of a reversible supramolecular polymer solution mixed with nanospheres

Abstract

Theory is presented for the phase stability of mixtures containing nanospheres andnon-adsorbing reversible supramolecular polymers. This was made possible byincorporating the depletion thickness and osmotic pressure of reversible supramolecularpolymer chains into generalized free-volume theory, recently developed for investigating thephase behaviour of colloidal spheres mixed with interacting polymers (Fleer and Tuinier2008 Adv. Colloid Interface Sci. 143 1–47). It follows that the fluid–fluid phasestability region where reversible supramolecular polymer chains can be mixed withnanospheres is sensitive to the energy of scission between the monomers and to thenanoparticle radius. One can then expect the fluid–fluid coexistence curves to have astrong dependence on temperature and that shifting of phase boundaries withina single experimental system should be possible by varying the temperature.The calculations reveal the width of the stability region to be rather small. Thisimplies that phase homogeneity of product formulations containing reversiblesupramolecular polymers is only possible at low nanoparticle concentrations.