Highly oriented and ordered double-helical morphology in ABC triblock terpolymer films up to micrometer thickness by solvent evaporation

Abstract

A triblock terpolymer, polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM), formed a double-helical nanoscale structure, composed of polybutadiene (PB) helical microdomains around hexagonally packed polystyrene (PS) cores in a poly(methyl methacrylate) matrix. The orientation of double-helical morphologies at various film thicknesses were studied using transmission electron microtomography, following solvent annealing and drying at a controlled solvent evaporation rate. The evaporation rate of the solvent and the film thickness were important factors in whether the double-helical microdomains were oriented parallel or perpendicular with respect to the substrate. In some cases, the perpendicularly aligned double-helical morphology extended several micrometers from the substrate to the air surface. A similar experiment using polystyrene-blockpoly(methyl methacrylate) diblock copolymer proved that the presence of helical PB microdomains around PS cylinders is the key factor in achieving a uniform orientation over several micrometers throughout the film thickness.

Isoporous Block Copolymer Membranes

“…A polystyrene‐ block ‐polybutadiene‐ block ‐poly(methyl methacrylate) triblock terpolymer known to form a helical morphology showed a spontaneous perpendicular alignment when spin‐cast from solution. The thickness depends on the concentration of the casting solution . A common aim of all these works was to control the alignment of the block copolymer domains, as the preferential perpendicular alignment of the often used cylinder‐forming and less often used lamellae‐forming block copolymers with respect to the substrate is a key issue for many potential applications, where nanostructured surfaces or nanostructured thin films are required.…”

Formation of Thin, Isoporous Block Copolymer Membranes by an Upscalable Profile Roller Coating Process—A Promising Way to Save Block Copolymer

“…However, some of these techniques only work in a batch mode like the spin coating approach, which is prominent in the solar cell industry or DVD production and can homogenously cover 30 cm diameter samples on smooth substrates like silicon wafers. Spin coating has also been used in various studies on BCP self-assembly in thin films [ 43 , 44 ], but it cannot be transferred to a roll-to-roll (R2R) process for larger areas in contrast to e.g., profile roller coating or doctor blade casting.…”

Emerging double helical nanostructures

“…Besides, Jinnai et al reported the visualization of a three-dimensional double helical morphology for a polystyrene-b-polybutadiene-b-poly-(methyl methacrylate) (PS-PB-PMMA) triblock terpolymer, which was composed of PB helical domains around hexagonalpacked PS cylinder cores in a PMMA matrix. 31,32 The orientation of such tirblock polymer double helices was achieved through subsequent solvent annealing and drying at a controlled solvent evaporation rate. 31 It should be noted that the self-assembly of organic molecules into double helical structures is always constructed along with more complicated self-organization schemes than expected.…”

“…31,32 The orientation of such tirblock polymer double helices was achieved through subsequent solvent annealing and drying at a controlled solvent evaporation rate. 31 It should be noted that the self-assembly of organic molecules into double helical structures is always constructed along with more complicated self-organization schemes than expected. On one hand, a long aging process is always required.…”