DPD Simulations of Homopolymer-Copolymer-Homopolymer Mixtures: Effects of Copolymer Structure and Concentration

Blends prepared by mixing incompatible homopolymers with a compatibilizing copolymer attract high technological interest due to their self-assembling behavior. In the present work, 281 dissipative particle dynamics (DPD) simulations are performed in order to evaluate the influence of copolymer microstructure and concentration on properties of these systems. The results show that alternate copolymers are arranged between the homopolymeric phases while nanodomains rich in each of the components are formed in the copolymeric matrix. Dispersion in block lengths increases the size of these nanodomains, so that they can properly allocate homopolymer chains. Besides, dispersions in chain lengths and chemical compositions of diblock copolymers, which can form self-assembled mesostructures, also lead to development of larger mesophase domains. Larger dispersions of chain lengths and chemical compositions cause the increase of the amount of copolymers necessary to bring about changes in the mixing behavior, when compared to non-dispersed copolymers. It can be concluded that microstructural properties of the copolymer exert a decisive impact on molecular interactions and, consequently, on the characteristics of the mesophases generated during the blending process. Therefore, microstructure control methods, stemming from both polymer-reaction engineering and polymer-purification techniques, are important for the design and resulting performance of the analyzed blends.