Enabling nanotechnology with self assembled block copolymer patterns

Heterogeneous materials in which the characteristic length scale of the filler material is in the nanometer range-i.e., nanocomposites-is currently one of the fastest growing areas of materials research. Polymer nanocomposites have expanded beyond the original scope of polymer-nanocrystal dispersions for refractive-index tuning or clay-filled homopolymers primarily pursued for mechanical reinforcement, to include a wide range of applications. This article highlights recent research efforts in the field of structure formation in block copolymer-based nanocomposite materials, and points out opportunities for novel materials based on inclusion of different types of nanoparticles. The use of block copolymers instead of homopolymers as the matrix is shown to afford opportunities for controlling the spatial and orientational distribution of the nanoelements. This, in turn, allows much more sophisticated tailoring of the overall properties of the composite material.

Block copolymer nanocomposites : Perspectives for tailored functional materials

A brief overview is provided of recent developments in the use of block copolymer self-assembly to create morphologies that may be used to template the fabrication of nanostructures in other materials. The patterning of semiconductor surfaces using block copolymer film masks and the production of high-density arrays of magnetic domains are discussed. The use of block copolymer micelles as 'nanoreactors' to prepare metal and semiconductor nanoparticles is considered, and methods to pattern nanoparticles are highlighted. A number of approaches to design nanocapsules are summarized. Finally, applications of bulk nanostructures to make mesoporous materials with controlled pore structures and sizes, or to create photonic crystals, are discussed.

https://iopscience.iop.org/article/10.1088/0957-4484/14/10/201/pdf

Nanostructure fabrication using block copolymers

Materials exhibiting three-dimensional (3D) linear dispersion relations between frequency and wavevector are expected to display a wide range of interesting phenomena. 3D linear point degeneracies between two bands (“Weyl points”) have yet to be observed. Based on analytical and numerical analysis, researchers predict Weyl point formation in 3D photonic crystals.

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Weyl points and line nodes in gyroid photonic crystals

Complex three-dimensional biophotonic nanostructures produce the vivid structural colors of many butterfly wing scales, but their exact nanoscale organization is uncertain. We used small angle X-ray scattering (SAXS) on single scales to characterize the 3D photonic nanostructures of five butterfly species from two families (Papilionidae, Lycaenidae). We identify these chitin and air nanostructures as single network gyroid (I4132) photonic crystals. We describe their optical function from SAXS data and photonic band-gap modeling. Butterflies apparently grow these gyroid nanostructures by exploiting the self-organizing physical dynamics of biological lipid-bilayer membranes. These butterfly photonic nanostructures initially develop within scale cells as a core-shell double gyroid (Ia3d), as seen in block-copolymer systems, with a pentacontinuous volume comprised of extracellular space, cell plasma membrane, cellular cytoplasm, smooth endoplasmic reticulum (SER) membrane, and intra-SER lumen. This double gyroid nanostructure is subsequently transformed into a single gyroid network through the deposition of chitin in the extracellular space and the degeneration of the rest of the cell. The butterflies develop the thermodynamically favored double gyroid precursors as a route to the optically more efficient single gyroid nanostructures. Current approaches to photonic crystal engineering also aim to produce single gyroid motifs. The biologically derived photonic nanostructures characterized here may offer a convenient template for producing optical devices based on biomimicry or direct dielectric infiltration.

/pdf/structure-function-and-self-assembly-of-single-network-22kg2elftp.pdf

Structure, function, and self-assembly of single network gyroid (I4132) photonic crystals in butterfly wing scales

Band structures of three dimensionally periodic bi- and tricontinuous cubic structures have been calculated using the plane-wave method for solving Maxwell's equations. In particular, we consider the single primitive, single diamond, single gyroid, double primitive, double gyroid, and double diamond level surface families as examples of such structures found in self-organizing systems. We also provide design guidelines for creating three-dimensional photonic crystals with a complete photonic band gap from block copolymer systems and other self-organizing systems.

N. Yufa

Papers

Photonic properties of bicontinuous cubic microphases