High aspect ratio cylindrical microdomains oriented vertically on the substrate using block copolymer micelles and temperature-programmed solvent vapor annealing

Abstract

We report a novel, yet simple, method for the preparation of high aspect ratio cylindrical microdomains oriented vertically on a substrate by using block copolymer micelles and temperature-programmed solvent vapor annealing. Multilayered spherical micelles were first prepared by spin-coating of polystyrene-block-poly(4-vinylpyridine) copolymer (PS-b-P4VP) in toluene solution on a silicon wafer.When temperature-programmed solvent vapor annealing was performed, the spherical micelle cores consisting of P4VP chains were transformed into vertically oriented cylindrical microdomains spanning the entire film thickness up to 550 nm corresponding to the aspect ratio of 15.2. Since nitrogen in the P4VP block could be easily coordinated with many metal precursors, we also fabricated a high density array of gold nanoparticle/polymer nanocomposite nanorods oriented vertically on the substrate.

Isoporous Block Copolymer Membranes

“…The application of a carefully controlled temperature protocol during solvent vapor annealing was demonstrated to have a strong influence on the alignment of cylindrical polystyrene‐ block ‐poly(4‐vinylpyridine) diblock copolymers (PS‐ b ‐P4VP), which tend to align parallel to the substrate . By vapor annealing a transformation of the alignment of the microphase boundaries from parallel to perpendicular with respect to the substrate was achieved . PS‐ b ‐P4VP is a strongly segregated diblock copolymer and will be further discussed later in this paper.…”

“…Besides spin‐coating or dip‐coating also spraying or electrospraying of block copolymer solutions on a solid substrate have been demonstrated to yield well‐aligned morphologies in thin films . The application of a carefully controlled temperature protocol during solvent vapor annealing was demonstrated to have a strong influence on the alignment of cylindrical polystyrene‐ block ‐poly(4‐vinylpyridine) diblock copolymers (PS‐ b ‐P4VP), which tend to align parallel to the substrate . By vapor annealing a transformation of the alignment of the microphase boundaries from parallel to perpendicular with respect to the substrate was achieved .…”

Ligand-free synthesis of gold nanoparticles incorporated within cylindrical block copolymer films

“…The majority of the studies focused so far on lamellar nanostructures, but oriented cylinders could provide a stronger confinement of AuNPs and offer different optical anisotropies than lamellae. However, very few methods to include AuNPs in such cylinders embedded in copolymer films have been reported so far 20,21 . Note that, on the opposite, quite a few studies have made use of such cylinders or other block copolymer morphologies as templates to produce 2D arrays of nanoparticles 22,23,24,25,26 .…”

Combination of temperature and saturated vapor annealing for phase separation of block copolymer

“…The periodical pattern can be prepared by the annealing in solvent vapor, temperature annealing or directly during spin‐coating deposition from selective solvent mixtures . In the case of the solvent vapor annealing, there are several key issues which influence the resulting morphology: choice of the suitable solvent, method of solvent annealing (static or dynamic), applied temperature, duration of solvent treatment, substrate and film thickness …”

“…The resulting orientation of the nanodomains and the quality of a film play a crucial role for the further application. Thus far, many studies have been dealing with the aforementioned parameters, but standardization of this technique for utilization in mass production has not been presented yet.…”