Compatibilization Efficiency of Additives in Homopolymer Blends: A Dissipative Particle Dynamics Study

We study the compatibilizing effect of copolymers of different architectures on the interface between two incompatible polymer phases by dissipative particle dynamics. Three base polymer systems are investigated, namely weakly incompatible (interspecies repulsion parameter of the dissipative particle dynamics interaction alpha(AB): 25 < alpha(AB) < 30), intermediate-incompatible (30 <= alpha(AB) < 40), and strongly incompatible systems (alpha(AB) >= 40). We find that the compatibilization efficiency of all regular block copolymers in strongly incompatible systems can be predicted by a power-law function, which contains the Flory-Huggins interaction parameter, the areal concentration, and the mean block length of the compatibilizer. Regular multiblock copolymers have better compatibilization performance compared to the symmetric diblock copolymers at the same areal concentration. This is because smaller amounts of the multiblock copolymer are required to saturate a given interfacial area. For unsymmetric diblock copolymers in strongly incompatible systems, we find additionally that the length of the shortest block is a more important determinant for the compatibilization efficiency than the ratio of block lengths. Our work reveals the involved mechanisms of the compatibilization process, and it provides a promising route to predict the compatibilization efficiency of differently structured copolymer additives in the respective polymer blends.

Automated summary

Our study reveals that in strongly incompatible systems, regular multiblock copolymers show better compatibilization performance compared to symmetric diblock copolymers at the same areal concentration. Additionally, for unsymmetric diblock copolymers in strongly incompatible systems, the length of the shortest block is a more important determinant for the compatibilization efficiency than the ratio of block lengths.