Microphase Separation of Statistical Multiblock Copolymers

Abstract

Random multiblock copolymers are characterized by a number of parameters, and their self-assembly is controlled, in particular, by correlations in monomer unit sequences. We investigate the microphase separation of random multiblock copolymers composed of A and B homo-oligomers (macromonomers) in melts. The copolymer synthesis and self-assembly are studied by computer simulations using the dissipative particle dynamics technique. The copolymers are formed by irreversible step-growth polymerization in an equimolar melt of end-functionalized macromonomers of length M up to a high conversion degree. Correlations between macromonomers of different types along the chains are controlled by the reaction probabilities. The molar mass and block mass distributions are described for linear macromolecules and for cycles. Macromonomer sequences in linear chains are well described by the first-order Markov statistics. With an increase in the Flory−Huggins parameter χ, microphase separation into a lamellar structure, for close-to-alternating block copolymers, and into irregularly arranged domains, for Bernoullian sequences of macromonomers, occurs. The transition χM values are approximately twice those obtained with weak segregation theory [Fredrickson, G. H.et al.Macromolecules1992, 25, 6341−6354] and approximately half the values for which microphases were previously detected in the simulations of random copolymer melts [Gavrilov, A. A.et al.J. Chem. Phys.2013, 139, 224901]. Microphase separation is described by the static structure factor and local composition, besides the block positions are monitored visually. The lamellar thickness H is always between the unperturbed sizes of one-and two-macromonomer blocks, and we characterize the separation as a moderate segregation regime. For the close-to-alternating block copolymers at a fixed χ, the thickness scales with the average block length approximately as H ∼ N̅ bl 2/3 that is in agreement with the theoretical description (Supporting Information) considering the elastic response of the shortest blocks only.

Intrinsically Elastic Semiconductors through Aldehyde–Amine Polycondensation and Its Application on Stretchable Transistor

“…This allowed microphase separation to form a double continuous phase structure. 47 Therefore, following works are focused on the performance comparison between P(DPP-DPP) and P(DPP-DPP)-PDMS 0.4 .…”

Molecular Architecture of Multiblock Copolymers Synthesized by the Chain Shuttling Technology

“…The effect of dispersity on orderorder microphase transitions is not discussed, referring the interested readers to general reviews. [68][69][70][71][72][73][74][75][76]…”

Understanding the pore structure evolution of polyethylene separator with dissipative particle dynamics simulation

“…[34][35][36][37] Considering the separator thickness (≥5 μm) and computational efficiency, meso-scale DPD simulations are preferred to study the microstructure of polymer in shear processing. 37,38 For example, shearinduced micro-scale phase separation has been studied for phospholipid cylinders in aqueous solution and the correlation between the microstructure and shear rate has been illustrated. 39 Also, the DPD simulation has been applied in surfactant-water-oil system 40 and poly(methyl methacrylate)-graphene system 41 mixing, and the effects of temperature, salt content, water/oil ratio, shear rate, and surfactant chemical structure on the interfacial behavior and stability of microemulsions were studied.…”

“…multi-component polymerization processing, and biological processing. [34][35][36][37] Considering the separator thickness (≥5 μm) and computational efficiency, meso-scale DPD simulations are preferred to study the microstructure of polymer in shear processing. 37,38 For example, shearinduced micro-scale phase separation has been studied for phospholipid cylinders in aqueous solution and the correlation between the microstructure and shear rate has been illustrated.…”

“…The atomic‐scale modeling (such as molecular dynamics, MD) and meso‐scale modeling (such as dissipative particle dynamics, DPD) have been applied to study the multi‐phase structure evolution in ionic liquids, multi‐component polymerization processing, and biological processing 34–37 . Considering the separator thickness (≥5 μm) and computational efficiency, meso‐scale DPD simulations are preferred to study the microstructure of polymer in shear processing 37,38 . For example, shear‐induced micro‐scale phase separation has been studied for phospholipid cylinders in aqueous solution and the correlation between the microstructure and shear rate has been illustrated 39 .…”