Morphology of symmetric block copolymer in a cylindrical pore

Abstract

The influence of confinement on morphology formation in copolymer systems is an important area of interest in theoretical research. We apply dynamic density functional theory to investigate the effect of pores on the morphology formation in a symmetric diblock copolymer system. The pore is represented by a perfect cylindrical tube. Porous systems are important in biology and are gaining interest for applications in nanotechnology. We show that for the pore sizes under investigation two equilibrium morphologies are possible depending on the surface interaction: a perpendicular or slab morphology and a parallel or multiwall tube morphology. The latter is referred to in the article as dartboard morphology. In the dynamic pathway towards this morphology an intermediate metastable helical phase is found. An important observation is that, for a wide range of pore radii and variations of polymer chain length, no mixed parallel/perpendicular morphologies were found: All observed morphologies are insensitive to the pore diameter.

Phase Behavior of Copolymers Confined in Multi-Walled Nanotubes: Insights from Simulations

“…The morphology shown in Figure 1b is different, accordingly, from that shown in Figure 1a. Notably, similar structures confined in the single-walled nanotubes were also found by Sevink et al [49] and Wang et al [50]. Obviously, both the incommensurability and the surface preference affect the formation of morphologies.…”

Gyroid-Forming Diblock Copolymers Confined in Cylindrical Geometry: A Case of Extreme Makeover for Domain Morphology

“…In this case, the wall of the confining pore is strongly attractive to the majority The one-ring lamella is similar to that observed for symmetric DBCPs when confined in selective pores [16][17][18][19][20][21][22][23][24][25].…”

“…The morphologies shown in Figure 3 can be compared with those obtained from the cylinder-or lamella-forming DBCPs under the cylindrical confinement [16][17][18][19][20][21][22][23][24][25][26][27][28]. We notice that helices and stacked toroids, frequently observed in the cylinder-forming system inside majority-selective pores, never occur in the gyroid-forming systems.…”

“…He et al [16] and Sevink et al [17] studied the self-assembled morphologies of symmetric DBCPs confined in cylindrical pores using Monte Carlo and dynamical density functional simulations, respectively. They observed concentric lamellae for cylindrical pores with an inner surface that strongly prefers one component of the DBCP over the other [16] and lamellae perpendicular to the pore axis (perpendicular lamellae, or stacked disks) for cylindrical pores with neutral surfaces [17]. Recently, Li et al performed real-space selfconsistent field theoretic (SCFT) calculations in two dimensions and constructed a phase diagram for DBCP melts confined in a circular geometry [18].…”

Helical, angular and radial ordering in narrow capillaries

“…-During the last years there has been large interest in the behavior of block copolymer (basically diblock copolymer) melts confined in narrow capillaries, which were studied both experimentally [1-6] and via computer simulation [7][8][9] as well as by numerical calculations within the self-consistent field theory [1,10,11]. The most characteristic of these morphologies are lamellae ordered normal to the cylinder axis z (slab morphology [10] ) and coaxial shells or multiwall morphologies [7,10] as well as various helices [1,8,9], the morphologies' symmetry being strongly depended on the ratio of the gyration radius R G of the diblock macromolecules under consideration and the radius R of the cylinder the macromolecules are confined to. However, some important issues have not been addressed yet.…”