Analysis of the effect of the interaction parameters of copolymer blocks on their efficiency in reducing the interfacial tension between the components of immiscible polymer blends

Block and graft copolymers with blocks that are identical to, miscible with or adhere to related components of a polymer blend can serve as compatibilizers. The relatively simple models established by Leibler and Noolandi provide the basis for addressing the influence of partial interaction parameters between the individual segments of two homopolymers and one copolymer and the influence of the copolymer block length ratio on the compatibilization efficiency. The maximum compatibilization efficiency for both the wet and dry brush formulae is obtained for a slightly longer chain of units compatible with the dispersed phase than that compatible with the matrix. A negative interaction parameter between a copolymer block and any homopolymer leads to lower copolymer contents at the interface and thus to a weaker compatibilization effect. If the units of one block of copolymer are miscible with one of the homopolymers and the units of the second block are immiscible with the second homopolymer, the copolymer content at the interface is lower than that when the mentioned interaction parameters are zero, and the compatibilization effect becomes weaker.