Copolymer—homopolymer mixtures in a nanopore

Abstract

We have performed the cell dynamics simulation with the time-dependent Ginzburg—Landau theory to study the self-assembled morphology of A—B diblock copolymers and C homopolymers in a neutral nanopore. The nanopore diameter and length are systematically varied to examine their effects on the structures of various morphologies and their phase transition. From the simulation, it is observed that the equilibrium morphology of the confined system is sensitive to pore diameter D and pore length Lpore, the phase behavior in neutral nanopores is due to an interplay of two factors: the surface effect and the extension effect. When the nanopore length and the lamellae spacing are not commensurate, the surface effect prevails at small nanopores (small diameters or short lengths), the extension effect takes over at larger nanopores (large diameters or long lengths). When the nanopore length and the lamellae spacing are commensurate, the surface effect dominates. Furthermore, the interactions between different monomers are also discussed and we obtain a transition from a tilted pancakes/cylinder structure (Ltilted⊥) to a concentric cylindrical structure with defects and to a concentric cylindrical structure (L‖). We also investigate the effect of the relative concentrations of diblock copolymer—homopolymer and obtain a transition in which the position of the C blocks changes from the outer of the cylinder to the middle of the cylinder and then to the inner of the cylinder with the concentration of the C blocks decreasing.

Blending Homopolymers for Controlling the Morphology Transitions of Block Copolymer Nanorods Confined in Cylindrical Nanopores

“…35 In addition, Zhang et al investigated the block copolymer/homopolymer morphologies confined in cylindrical nanopores. 36 Morphologies similar to our experimental results, such as the multihelical morphologies, are obtained from these simulation works; the simulation parameters, however, are not identical to our experimental conditions because the block copolymer chains are introduced into the nanopores by solvent vapor-induced wetting in our works. Therefore, we believe that our research results should provide useful information on future simulation projects of block copolymers in confined geometries.…”

“…Zvelindovsky et al also studied the microphase separation of block copolymers confined in cylindrical nanopores . In addition, Zhang et al investigated the block copolymer/homopolymer morphologies confined in cylindrical nanopores . Morphologies similar to our experimental results, such as the multihelical morphologies, are obtained from these simulation works; the simulation parameters, however, are not identical to our experimental conditions because the block copolymer chains are introduced into the nanopores by solvent vapor-induced wetting in our works.…”

Microphase transitions of block copolymer/homopolymer under shear flow

“…Our simulations are carried out on L x × L y × L z = 64 × 64 × 64 cubic lattice, and the parameters are chosen to be A η = 1.3, A φ = 1.1, D 1 = 1.0, D 2 = 0.5, b 1 = 0.10, b 2 = 0.02, and M η = M φ = 1, the initial distributions of φ and η are specified by random uniform distributions in the range [−0.01, 0.01], in accordance with the previous work[67][68][69]. In this paper, all parameters are scaled, so all of them are dimensionless[52].…”

Structural Transformation of Diblock Copolymer/Homopolymer Assemblies by Tuning Cylindrical Confinement and Interfacial Interactions

“…The 2D confined assembly of diblock copolymer in nanochannels has been investigated via experimental ,, and simulative approaches. ,, Several factors, including the interfacial interaction and the confining strength, are proven to severely affect the assembly behavior, resulting in unconventional structures. Here we focus on the effect of homopolymer on the phase separation of diblock copolymers under 2D confinement, which is seldom reported in experiments …”