Optical Reflection from Unforbidden Diffraction of Block Copolymer Templated Gyroid Films

Abstract

We present material substitutions and optical characterization of block copolymer (BCP)-templated gyroid structures that are obtained from a volume-asymmetric polystyrene-b-poly­(methyl methacrylate) (PS-b-PMMA). In addition to the structural analyses reported earlier, we elucidate the optical responses to the nonaffine gyroid planes, in which the PMMA channels are complexed with Al2O3 by sequential infiltration synthesis and the organic components are further eliminated to produce an inorganic air–Al2O3 gyroid film. Grazing-incidence small-angle X-ray scattering measurements show that three-dimensional gyroid lattices are retained in both in-plane and out-of-plane directions through these material substitution processes. Our BCP-templated gyroid films respond to the middle UV wavelength from 200 to 300 nm, and peculiar optical reflectance peaks correlate with the unforbidden {110} diffraction spots. Together with the red- and blue-shifts of the reflectance peaks by the component substitutions, the air–Al2O3 gyroid structure reveals the high-amplitude spectrum due to the large refractive-index difference between channel and matrix.

Stabilizing Differential Interfacial Curvatures by Mismatched Molecular Geometries: Toward Polymers with Percolating 1 nm Channels of Gyroid Minimal Surfaces

“…Also, the electron beams generated from a high voltage of 200 kV can readily distort the real imaging due to the temporal heating on the polymers. Previous X-ray scattering studies have proved that nanostructured materials templated from double-gyroid mesophases often exhibit the forbidden {110} reflections, which arises from, for instance, the directional contraction in thin films that breaks the cubic symmetry. , …”

Curving and Twisting in Self-Assembly of Triblock Terpolymers Driven by a Chiral End Block

“…Recently, the Weyl points created by symmetry breaking of network structures in BCPs attracted great attention due to its possibility of obtaining specific photonic crystal behaviors . The symmetry breaking of DG and DD structures can be attributed to distortion, , network shifting, , or the imbalance in the two catenated networks . Lattice distortion is often formed during fast solvent evaporation.…”

Mesoporous Phenolic/POSS Hybrids Induced by Microphase Separation Arising from Competitive Hydrogen Bonding Interactions

“…The self-assembly of linear diblock copolymers in the bulk state, forming body-centered cubic (BCC), hexagonal-packing cylinder (HEX), double-gyroid (DG), and lamellae (LAM) structures, mediated by the interaction parameter (χ), volume fraction ( f ), and molecular weight ( N ), is being investigated widely because of their potential applications in nanopatterns, nanocomposites, drug delivery, and electronic and photonic devices. − Blending diblock copolymers with homopolymers, copolymers, nanoparticles, and organic–inorganic hybrids to vary the volume fractions and interaction parameters, mediated by hydrogen-bonding interactions, is another simple approach toward fabricating various self-assembled structures. − Recently, Frank–Kasper (FK) phases, including A15, σ, C14, and C15 phases, have also been observed in the phase diagrams of diblock copolymers through both experimental studies and theoretical predictions. − …”