Large-area, crack-free polysilazane-based photonic crystals

Zhang, Zongbo; Shen, Weizhi; Ye, Changqing; Luo, Yongming; Li, Shuhong; Li, Mingzhu; Xu, Caihong; Song, Yanlin

doi:10.1039/c2jm15137e

Cited by 25 publications

(29 citation statements)

References 30 publications

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“…In this technique, the preceramic polymer is mixed with sacrificial templates which are extracted during a later step, either by burn-off, thermal decomposition, etching, or leaching. A wide variety of sacrificial porogens have been used in combination with preceramic polymers, including salts, 27 silica beads, 28 wood, 29 as well as a number of conventional polymers such as PS, [30][31][32][33][34] PMMA, [35][36][37] low-density PE, 38 or PVA. 39 Schmalz and co-authors successfully produced porous polysilazane-derived silicon carbonitride (SiCN) by using ultra-high molecular weight polyethylene (UHMW-PE) as a sacrificial template.…”

Section: Introductionmentioning

confidence: 99%

Planar, Polysilazane‐Derived Porous Ceramic Supports for Membrane and Catalysis Applications

2015

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Porous, silicon carbonitride-based ceramic support structures for potential membrane and catalysis applications were generated from a preceramic polysilazane precursor in combination with spherical, ultrahigh-molecular weight polyethylene microparticles through a sacrificial filler approach. A screening evaluation was used for the determination of the impact of both porogen content and porogen size on pore structure, strength, and permeability characteristics of planar specimens. By optimizing both the composition as well as cross-linking parameters, maximum characteristic biaxial flexural strengths of 65 MPa and porosities of 42% were achieved. The evolution of an interconnected, open-pore network during thermal porogen removal and conversion of the preceramic polymer led to air permeabilities in the order of 10−14 m2. The materials were further exposed to long-term heat treatments to demonstrate the stability of properties after 100 h at 800°C in oxidizing, inert, and reducing environments. The determined performance, in combination with the versatile preparation method, illustrates the feasibility of this processing approach for the generation of porous ceramic support structures for applications at elevated temperatures in a variety of fields, including membrane and catalysis science.

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Section: Introductionmentioning

confidence: 99%

Planar, Polysilazane‐Derived Porous Ceramic Supports for Membrane and Catalysis Applications

2015

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“…Song's group proposed that the crack can be avoided by assembling the latex spheres on a flexible Al foil substrate or a superhydrophobic and low-adhesion substrate to relieve the tensile stress, 25,26 which was consistent with the method of crystallization on a fluid Ge/Hg substrate proposed by Zental, or by self-assembly on an elastomeric polydimethylsiloxane (PDMS) matrix proposed by Cho's group. 29,30 While the pre-treatment processing of the substrate and the fabrication of inverse opal PCs are complicated and expensive, and are not economical in the preparation of large-area PCs, the addition of polymer will inevitably reduce the contrasts of the refractive index of the PCs, 6,7 which will result in poor light quality of the PCs. 31 Kang's group and Sawada's group also fabricated crack-free PCs by addition of monomers to a suspension of latex spheres for polymerization during the assembly process or by addition of polymer to avoid shrinkage of the latex spheres.…”

Section: Introductionmentioning

confidence: 99%

Coordination-bond-driven fabrication of crack-free photonic crystals

et al. 2016

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The self-assembled fabrication of large-area opal photonic crystals (PCs) that are free of cracks has remained a challenge which greatly limits the practicality of such a structure in optical and electronic applications. We report a new route in this paper for fabricating centimeter scale crack-free opal PC films in which the latex spheres are bound together through coordination bonds. The elimination of cracks in the PCs is attributed to the formation of metal ion-polymer latex spheres coordination complexes which is confirmed by shifts of the binding energy of the metal ion after the reaction. The coordination bonds enhance the interactions between the polymer latex spheres, which can neutralize the adhesion stress caused by the substrate and tension stress caused by the shrinkage of the latex spheres during the evaporation of solvent. The as-prepared PC films show a uniform diffraction color and excellent reflection properties, which proves that the formation of coordination bonds does not weaken the contrasts of the refractive index or the optical quality of the PCs. This facile fabrication of large area, crack-free opal PCs will offer significant insight into the preparation and applications of PCs in optical devices. † Electronic supplementary information (ESI): Characterization of the morphology and size dispersion of the latex spheres and optical microscopy images of the PCs. See

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“…Some examples of mechanical properties of opaline structures can be found in the literature. These works investigated polymer, metal, and ceramic‐based opals. Toivola et al investigated silica inverse opals by nanoindentation using a Berkovich indent.…”

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confidence: 99%

Self‐Assembled Ultra High Strength, Ultra Stiff Mechanical Metamaterials Based on Inverse Opals

et al. 2015

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Inverse opals are most widely used as photonic crystals for ultraviolet, optical, and infrared applications. [1] These highly interconnected porous structures are also attractive for applications such as sensors, fuel cells, filters, and catalysts. [2] At the same time, engineers are aiming for lightweight structures with optimized mechanical strength, often inspired by nature's cellular materials with foam-like structures such as sponges, [3] trabecular bone, [4] or plant parenchyma. [5] The resultant optimized strut-based structures have shown high stiffness-and compressive strength-to-weight ratios, [6][7][8][9] but can suffer from strut buckling and a lack of mass production techniques. Here, we show that mechanical metamaterials based on ceramic inverse opaline structures with densities in the range of 330-910 kg m À3 are not only suitable as photonic crystals but also show better stiffness-and compressive strength-to-weight ratios compared to microfabricated optimized strut-based structures, [6][7][8][9] but lower than carbon nanoframes fabricated by interference lithography. [10] Pure silica inverse opal structures and silica inverse opals whose pores have been internally coated by a thin TiO 2 layer have been fabricated and their structural and mechanical behavior was investigated. Our experimental results, supported by numerical simulations, show that these arch-shaped porous structures outperform both strut-based and honeycomb structures due to their nearly isotropic mechanical response.The silica inverse opal films presented here are fabricated by vertical co-assembly based on the procedure described by Hatton et al. [11] Monodisperse colloidal polystyrene (PS) spheres were mixed in a water-based suspension containing tetraethylorthosilicate (TEOS) solution and vertically assembled on soda-lime silica glass. The resulting FCC opaline structure was calcined at 500°C for 30 min to burn out the PS template leaving an inverse-FCC opaline structure of nanoporous amorphous silica in which the adjacent pores are interconnected by %170 nm diameter holes (Figure 1a). Some samples were subsequently coated with an amorphous layer of TiO 2 by atomic layer deposition (ALD). After full crystallization to anatase, the layer thickness was %28 nm (Figure 1b). The specular reflection in Figure 1c shows the characteristic reflection peaks, which can be tuned by both the pore diameter and/or the TiO 2 coating.The effective density of the silica inverse opals was estimated by four independent methods: gravimetric, pycnometric, and two opticals. All four methods yield a comparable density of 330 kg m À3 AE 10%. The effective density of the TiO 2 ALD-coated silica inverse opals was estimated gravimetrically and optically to be 910 kg m À3 AE 10%. Detailed information can be found in the Supporting Information.Some examples of mechanical properties of opaline structures can be found in the literature. These works investigated polymer, [12,13] metal, [14] and ceramic-based [14][15][16] opals. Toivola et al. [15] investigated s...

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Large-area, crack-free polysilazane-based photonic crystals

Cited by 25 publications

References 30 publications

Planar, Polysilazane‐Derived Porous Ceramic Supports for Membrane and Catalysis Applications

Planar, Polysilazane‐Derived Porous Ceramic Supports for Membrane and Catalysis Applications

Coordination-bond-driven fabrication of crack-free photonic crystals

Self‐Assembled Ultra High Strength, Ultra Stiff Mechanical Metamaterials Based on Inverse Opals

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