Theory of Long-Range Interactions in Polymer Systems

(Received 15 July 1996, received in final form 12 August 1996, accepted 2 September 1996)

Abstract
A mean-field theory of inhomogeneous polymer systems is developed in order to include the finite molecular weight effects. A general analytical expression for the conformational free energy providing a bridge between strong and weak segregation limits is derived. The general results are further employed to obtain the dependence of interfacial tension in polymer blends on the molecular weights of the components. A long-range repulsion (induced by the presence of polymer ends) between solid walls in polymer solutions and interfaces in polymer blends is predicted, the effect being formally due to finite molecular weight corrections. It is shown that this repulsion can lead to a stabilization of colloidal systems with small amount of added polymer even in the absence of any specific interactions between polymer and particles. It is also shown that the end-induced repulsion can lead to freezing of domain structures at late stages of demixing in polymer blends.