WiFi-like Nanostructures from Confinement of Block Copolymer Microdomains in Asymmetric Hemisphere Nanocavity

Abstract

We investigated the morphology of lamellae-forming polystyrene-block-poly(methyl methacrylate) copolymer (PS-b-PMMA) confined in asymmetric hemisphere nanocavities which were prepared by oblique angle deposition of gold with various thicknesses. When the thickness of the deposited gold layer (t Au) was 0.5L 0 of PS-b-PMMA (L 0 is the lamellar domain spacing of PS-b-PMMA in bulk), concentric lamellar patterns were formed on the top surface of the nanocavities. Interestingly, at t Au = 1L 0, WiFi-like nanopatterns were observed on the top surface. This is because of the reduction of dislocations of PS and PMMA lamellar microdomains near the center of the nanocavity. The experimentally observed morphologies are consistent with prediction by self-consistent field theory. In addition, the inner wall of the hemispherical nanocavity was modified by grafting three different polymer brushes (PS, PMMA, and PS-r-PMMA) to change the affinity to each block. When the nanocavity was grafted by PMMA, WiFi-like nanopatterns were observed. On the other hand, laterally stacked U-shaped nanopatterns were formed in a nanocavity grafted by PS-r-PMMA with neutral affinity to PS and PMMA. We also fabricated an array of silver WiFi-like nanopatterns composed of laterally stacked split-ring resonators after selective silver deposition only on the PS microdomains. They showed unique plasmonic resonances depending on the polarization angle of incident light in near-infrared (NIR) wavelengths. The nanopatterns with broken symmetry obtained in this study can be used in advanced optical devices for structural coloration and optical anticounterfeiting.

Ultrabroadband absorptive refractory plasmonics for photocatalytic hydrogen evolution reactions

“…1a. First, an AAO template with a height of 10 μm, a distance between two neighboring pores of 500 nm, and a pore diameter of 470 nm was fabricated using the two-step anodization method and widening process [31][32][33] . Then, TiO 2 (5 nm) was deposited on the AAO template through ALD.…”

Preparation, Properties, and Bioapplications of Block Copolymer Nanopatterns

“…istry of the template, the thickness of the casted BCP, and the size of the blocks are crucial for the nucleation of the microdomains and can be tailored to induce different organization at the nanoscale within the same micropattern (Figure 6B,C). [36a,37] Recent works have explored more complex templates such as hemisphere [39] and asymmetric hemisphere nanocavities, [40] at which different confinement of the casted BCP drives the formation of patterns with customized size and morphology. These works have shown the potential of the template-driven assembly of BCP for generating a great diversity of complex and defect-free morphologies: straight lines, concentric circles, spirals, square arrays of dots, bends, T-junctions are just a few examples of the versatility of this method (Figure 6D).…”

“…Recent works have explored more complex templates such as hemisphere [ 39 ] and asymmetric hemisphere nanocavities, [ 40 ] at which different confinement of the casted BCP drives the formation of patterns with customized size and morphology. These works have shown the potential of the template‐driven assembly of BCP for generating a great diversity of complex and defect‐free morphologies: straight lines, concentric circles, spirals, square arrays of dots, bends, T‐junctions are just a few examples of the versatility of this method (Figure 6D).…”

“…These works have shown the potential of the template‐driven assembly of BCP for generating a great diversity of complex and defect‐free morphologies: straight lines, concentric circles, spirals, square arrays of dots, bends, T‐junctions are just a few examples of the versatility of this method (Figure 6D). [ 18,36b,37a,39,40 ] However, the widespread implementation of this method is hindered by the specific and often costly equipment needed for the preparation of the substrates. So far, it is mainly employed in the fabrication of electronic devices and its use in the context of biological applications remains limited, despite the immense possibilities that it offers.…”

Constructing a Comprehensive Nanopattern Library through Morphological Transitions of Block Copolymer Surface Micelles via Direct Solvent Immersion

“…However, these structures are susceptible to the architecture or chemical nature of BCPs; thus, a single BCP structure can only yield limited structural versatility. Therefore, additional topographic/chemical modification of a substrate [46][47][48] or complicated synthesis of a specific BCP structure [34,40,43] is necessary to diversify the nanopatterns that can be achieved. In other words, a more practical methodology that can efficiently produce diverse nanostructures with good accessibility has not been realized.…”