A Shifted Double‐Diamond Titania Scaffold

Abstract

Photonic crystals are expected to be metamaterials because of their potential to control the propagation of light in the linear and nonlinear regimes.B iological single-network, triply periodic constant mean curvature surface structures are considered excellent candidates owing to their large complete band gap.However,the chemical construction of these relevant structures is rare and developing new structures from thermodynamically stable double-network self-organizing systems is challenging.Herein, we reveal that the shifted double-diamond titania scaffold can achieve ac omplete band gap.T he largest (7.71 %) band gap is theoretically obtained by shifting 0.332 c with the dielectric contrast of titania (6.25). At itania scaffold with similar shifted double-diamond structure was fabricated using ar everse core-shell microphase-templating system with an amphiphilic diblock copolymer and at itania source in am ixture of tetrahydrofuran and water,w hichc ould result in a2 .05-3.78 %gap.Various photonic structures have been exploited for coherent light scattering through periodic changing of refractive indices. [1] Thes ingle-diamond (SD) and single-gyroid (SG) structures,f ound in beetles exoskeletons and butterfly wing scales,e xhibit excellent photonic properties. [2] In particular, SD is known as a" champion" photonic structure because it exhibits the largest complete band gap (CBG) reported so far. [3] Thet hermodynamically favored bicontinuous doubleframework structures consisting of two identical intertwined labyrinths,f or example,d ouble-diamond (DD), doublegyroid (DG) and double-primitive (DP), are widely found, [4] however, they show no CBG as increasing the symmetry would suppress the photonic properties. [3] Thethermodynamically unstable single-network structures have been achieved only through physical holographic lithography, [5] direct laser writing, [6] replication of biological templates, [7] partial occupancy of the initially formed double-network template, [8] and the so-called alternating gyroid method by selective etching one of the original DG subnetworks to yield aSGtemplate. [9] Recently,H oe tal. reported ar andom-shifted DG silica structure that disrupts the inversion symmetry of the networks,leading to the partial photonic band gap related to the subgroup symmetry. [10] Thecorresponding TiO 2 structure can also be fabricated by the templated sol-gel reaction. [11] We reported macroporous silica with azimuthally shifted DD (SDD) frameworks through the self-assembly of an amphiphilic ABC triblock terpolymer in am ixture of tetrahydrofuran and water. [12] However,t he dielectric constant of the silica (3.9) was too low to lead to CBG.In this work, we used titania with high dielectric contrast (6.25) [10] to produce the desirable CBG features of the SDD structure.W ed etermined the band gap of the SDD titania scaffold with different space occupancya nd shift value,a nd compared it to SD and SG structures.T he multi-term nodal equations [13] were used as the structural analogue of these cons...

Electron Crystallographic Investigation of Crystals on the Mesostructural Scale

“…The concept of the crystals on a mesostructural scale is based on a periodic structure with the unit cell parameters ranging from nanometer scale to sub-micron. Relevant structures have been widely found in nature and artificial systems, such as butterfly wing scales (Saranathan et al, 2010; Winter et al, 2015; Corkery & Tyrode, 2017; Wilts et al, 2017), exoskeleton of beetles/weevils (Galusha et al, 2008; Wilts et al, 2012), mineralization templated from the natural species (Galusha et al, 2010; Mille et al, 2011, 2013; Wu et al, 2018), superstructures of inorganic nanoparticles (Zhang et al, 2017), self-assembly of surfactants and block copolymers and their inorganic replicas (Finnemore et al, 2009; Han et al, 2009, 2011, 2014 b , Hsueh et al, 2014; Cao et al, 2016; Li et al, 2017; Mao et al, 2017; La et al, 2018; Yang et al, 2019; Lin et al, 2020), etc. Compared to the traditional atomistic crystal structures, these mesostructured crystals contain highly organized networks or cavities arranged periodically and sometimes possess amorphous (or metal, metallic oxide, etc.)…”

Double diamond structured bicontinuous mesoporous titania templated by a block copolymer for anode material of lithium-ion battery

“…2(a). The observed signals can be indexed to the 101, 200/112, 121/103, 220/004 and 301 reflections of a tetragonal unit cell of a typical SDD lattice [39], demonstrating the SDD architecture of the TiO2 framework. The cell parameters are a = 90 nm and c = 127 nm, with a c/a ratio of ~2 .…”

“…Compared with the assemblies formed by small-molecule surfactants, BCP aggregates are much more stable and solid, thus being more appropriate to act as the templates for the synthesis of versatile functional materials of designed structures. To date, a few bicontinuousstructured inorganic nanomaterials, including SiO2, TiO2, and carbons, have been synthesized by employing BCP assemblies as soft templates, which includes two primary approaches [33][34][35][37][38][39][40][41]. One involves the self-assembly of BCPs into bicontinuous superstructures, which are then used as soft templates to produce inorganic replicates [37,38].…”

“…1(b)). The TIA is hydrolyzed and condensed in the PEO region under the acidic condition due to the hydrogen bonding interactions between the ethylene oxide units and the titania species [39]. By carefully controlled slow evaporation of solvents at 283 K for 7 days, two interwoven diamond labyrinths are formed through the cooperative self-assembly of the BCP template and the titania species.…”

“…3(c)-3(f). The adhered DD frameworks can be identified, however, they are shifted along the original <001> axis of the cubic unit cell of DD by approximately a quarter of the unit cell and the symmetry becomes tetragonal with a space group of I41/amd [35,39]. The unique shift along the <001>cub axis can be explained by the maximize of the contact area of the frameworks through the van der Waals interaction between hydrophobic surfaces [35].…”