Dissipative particle dynamics study on the interfacial structure and tension for polymer blends of different copolymer chemical composition distributions

Abstract

A dissipative particle dynamics (DPD) simulation is used to study the interfacial structure and tension for the polymer blends of different copolymer chemical composition distributions. Four chain lengths of diblock copolymers NAB = 10, 20, 40, and 60 with different microstructures are utilized for simulation. As the copolymer microstructure varied from the nondispersed symmetric diblock copolymer to the bidisperse asymmetric diblock copolymer mixtures, the asymmetry of the copolymer varied from f = 0.5 to 0.9. Our simulations show that (i) increasing the copolymer chain length NAB will significantly enhance the interfacial tension, which indicates that the chain length of the diblock copolymer is the most important factor affecting the compatibilization efficiency. Only when the copolymer chain length NAB = 10 can the asymmetry significantly affect the compatibilization efficiency, and the length of the shorter block is the decisive factor in the compatibilization efficiency of asymmetric diblock copolymers; (ii) with an increase in the asymmetry of the diblock copolymer from f = 0.5 to 0.9, the effective chain length of the diblock copolymer with compatibilization decreases, which results in a reduced number of compatibilized beads of copolymers. Thus, the symmetric block copolymer AB is more effective in reducing the interfacial tension than the asymmetric diblock copolymer mixtures at the same concentration; and (iii) The symmetric diblock copolymers enrich faster at the interfaces when elevating the copolymer concentration, which results in a faster reduction in the interfacial tension than that of the asymmetric bidisperse diblock copolymer mixtures. Our research work expands the understanding of polymer blends containing bidisperse asymmetric diblock copolymer mixtures.