Cylindrically confined assembly of diblock copolymer under oscillatory shear flow

TL;DR

This study explores how cylindrical confinement combined with oscillatory shear flow influences the self-assembly of diblock copolymers, revealing new morphologies and phase transitions useful for fabricating nanostructured materials.

Contribution

It introduces a phase diagram for diblock copolymer morphologies under combined confinement and shear, highlighting the interplay of field and confinement effects as a novel control method.

Findings

Different morphologies and phase transitions occur with varying D/L0 ratios.

Phase transitions are driven by the interplay of field and confinement effects.

Novel morphologies are identified under specific shear and confinement conditions.

Abstract

Manipulating the self-assembly nanostructures with combined different control measures is emerging as a promising route for numerous applications to generate templates and scaffolds for nanostructured materials. Here, the two different control measures are a cylindrical confinement and an oscillatory shear flow. We study the phase behavior of diblock copolymer confined in nanopore under oscillatory shear by considering different $D/L_0$ ($D$ is the diameter of the cylindrical nanopore, $L_0$ is the domain spacing) and different shears via Cell Dynamics Simulation. Under different $D/L_0$, in the system occurs different morphology evolution and phase transition with the changing of amplitude and frequency. Meanwhile, it forms a series of novel morphologies. For each $D/L_0$, we construct a phase diagram of different forms and analyze the reason why the phase transition occurs. We find that although the morphologies are different under different $D/L_0$, the reason of the phase transition with the changing of amplitude and frequency is roughly the same, all caused by the interplay of the field effect and confinement effect. These results can guide an experimentalist to an easy method of creating the ordered, defect-free nanostructured materials using a combination of the cylindrical confinement and oscillatory shear flow.