DESIGNING COMPATIBILIZERS TO REDUCE INTERFACIAL-TENSION IN POLYMER BLENDS

We use self-consistent mean field methods and analytical theory to det ermine the behavior of AB copolymers at the interface between two inco mpatible homopolymers, A and B. We calculate the reduction in interfac ial tension, gamma, resulting from the copolymers localizing at the A/ B interface. We examine the effects of chain length, composition, and molecular architecture on the efficiency of the copolymers. In particu lar, we compare the interfacial behavior of different linear copolymer s (random, alternating, and diblock) and various branched copolymers ( stars and combs). At fixed molecular weight, the diblock copolymers ar e the most efficient at reducing gamma. However, when we compare rando m and comb copolymers with diblocks at different molecular weights, we observe that the longer random or comb copolymers are more efficient than short diblocks. These studies allow us to predict the reduction i n interfacial tension produced by a wide variety of copolymers and, th ereby, permit a rational design of cost-effective and efficient compat ibilizers.