Direct interchain exchange reaction in a polymer blend: evolution of the block weight distribution

Abstract

AbstractThe kinetics of an interchain exchange reaction in homogeneous polymer blends is studied theoretically. A set of kinetic equations describing the evolution of the block weight distribution is derived. It is demonstrated that the process may be divided into a fast and a slow stage. The former results in the almost full disappearance of homopolymer chains. Simultaneously, the block weight distribution becomes close to the Flory distribution. In the course of the slow stage, the average block lengths decrease to values typical of a completely random copolymer. It is explicitly shown that for an initial blend of homopolymers characterized by the Flory distribution, the transient block weight distribution takes the Flory form starting from the onset of the reaction. The copolymer composition is proved to change in the course of the fast stage of the process. Previous attempts to address the problem are discussed.