Structural Color in Porous, Superhydrophilic, and Self‐Cleaning SiO<sub>2</sub>/TiO<sub>2</sub> Bragg Stacks

Wu, Ziling; Lee, Daeyeon; Rubner, Michael F.; Cohen, Robert E.

doi:10.1002/smll.200700084

Cited by 239 publications

(162 citation statements)

References 34 publications

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“…3,4 While in earlier publications the alternated deposition involved polycations and polyanions, over the last years it evolved to the combination of polymers (charged or not) and proteins [3][4][5][6][7][8] or inorganic particles. [9][10][11] The driving force for the stable layer association is entropic in nature and results from the release of counter-ions and water. 12,13 Issues concerning the dependence of thickness evolution, [14][15][16][17] morphology 18 and ionization (in the case of weak polyelectrolytes) 19 as a function of alternated deposition are important because they control film stability and, consequently, its final applications.…”

Section: Introductionmentioning

confidence: 99%

Structural aspects of polyanion and hydrophobically modified polycation multilayers on hydrophilic or hydrophobic surfaces

et al. 2012

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Multilayer films of carboxymethylcellulose (CMC), a polyanion, and bromide salts of poly(4-vinylpyridine) quaternized with linear aliphatic chains of 2 (ethyl) and 5 (pentyl) carbon atoms, coded as QPVP-C2 and QPVP-C5, respectively, were fabricated by layer-by-layer (LbL) self-assembly onto Si/SiO 2 wafers (hydrophilic substrate) or polystyrene, PS, films (hydrophobic substrate). The films were characterized by means of ex situ and in situ ellipsometry, atomic force microscopy (AFM), contact angle measurements and sum frequency generation vibrational spectroscopy (SFG). Antimicrobial tests were used to assess the exposure of pyridinium moieties to the aqueous medium. In situ ellipsometry indicated that for Si/SiO 2 the chains were more expanded than the PS films and both substrates systems composed of QPVP-C5 were thicker than those with QPVP-C2. For dried layers, the alkyl side group size had a small effect on the thickness evolution, regardless of the substrate. At pH 2 the multilayers showed high resistance, evidencing that the build-up is driven not only by cooperative polymer-polymer ion pairing, but also by hydrophobic interactions between the alkyl side chains. The LbL films became irregular as the number of depositions increased. After the last deposition, the wettability of QPVP-C2 or QPVP-C5 terminated systems on the Si/SiO 2 wafers and PS films were similar, except for QPVP-C2 on Si/SiO 2 wafers. Unlike the morphology observed for LbL films on Si/ SiO 2 wafers, PS induced the formation of porous structures. SFG showed that in air the molecular orientation of pyridinium groups in multilayers with QPVP-C5 was stronger than in those containing QPVP-C2. The exposure of pyridinium moieties to the aqueous medium was more pronounced when the LbL were assembled on Si/SiO 2 wafers.

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Section: Introductionmentioning

confidence: 99%

Structural aspects of polyanion and hydrophobically modified polycation multilayers on hydrophilic or hydrophobic surfaces

et al. 2012

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“…[74] Besides regular structures, more random frameworks can be generated with etching/oxidation, layer-bylayer, interfacial polymerization and sol-gel methods. [75][76][77][78][79][80][81][82][83][84][85][86] However, sometimes surface morphology change needs to be avoided when generating SLPL interfaces, hence changing the surface chemical state is an alternative choice, such as UV illumination and plasma treatment. [35,39,[87][88][89][90][91][92][93] Chemical vapor deposition can obtain SLPL interfaces by depositing a thin layer with chemical reactions.…”

Section: Introduction Of the Fabrication Methods To Generate Slpl Intmentioning

confidence: 99%

Superlyophilic Interfaces and Their Applications

et al. 2017

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Superlyophilic interfaces denote interfaces displaying strong affinity to diverse liquids, including superhydrophilic, superoleophilic, and superamphiphilic interfaces. When coming in contact with these interfaces, water or oil droplets tend to spread completely with contact angles close to 0°, presenting versatile applications including self‐cleaning, antifogging, controllable liquid transport, liquid separation, and so forth. Inspired by nature, scientists have developed various kinds of artificial superlyophilic (SLPL) interfaces in the past decades. In terms of dimensional characteristics, the artificial SLPL interfaces can be divided into four categories: i) 0D particles, whose dispersibility or catalytic performance can be notably enhanced by superlyophilicity; ii) 1D micro‐/nanofibers or nanotubes/channels, which can efficiently transfer liquids with SLPL interfaces; iii) 2D flat SLPL interfaces, on which different functional molecules can be deposited uniformly, forming ultrathin and smooth films; and iv) 3D structures, which can be obtained by either constructing 0D, 1D, or 2D SLPL materials separately or directly fabricating random SLPL frameworks, and can always be used as functional coatings or bulk materials. Here, natural and artificial SLPL interfaces are briefly introduced, followed by a short discussion of the limit between lyophilicity and lyophobicity, and then a snapshot of methods to generate SLPL interfaces is given. Specific focus is placed on recent achievements of constructing SLPL interfaces from zero to three dimensions. Following that, broad applications of SLPL interfaces in commercial areas will be introduced. Finally, a short summary and outlook for future challenges in this field is presented.

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“…Inorganic porous films using this principle can be used in a color-tunable sensor. Their mesoporous SiO 2 and TiO 2 multilayers can be fabricated by depositing precursor solutions by spin coating [41], dip coating [42] and layer-by-layer assembly [43].…”

Section: Multilayer Interferencementioning

confidence: 99%

Tunable structural color in organisms and photonic materials for design of bioinspired materials

Fudouzi

2011

Science and Technology of Advanced Materials

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In this paper, the key topics of tunable structural color in biology and material science are overviewed. Color in biology is considered for selected groups of tropical fish, octopus, squid and beetle. It is caused by nanoplates in iridophores and varies with their spacing, tilting angle and refractive index. These examples may provide valuable hints for the bioinspired design of photonic materials. 1D multilayer films and 3D colloidal crystals with tunable structural color are overviewed from the viewpoint of advanced materials. The tunability of structural color by swelling and strain is demonstrated on an example of opal composites.

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Structural Color in Porous, Superhydrophilic, and Self‐Cleaning SiO₂/TiO₂ Bragg Stacks

Cited by 239 publications

References 34 publications

Structural aspects of polyanion and hydrophobically modified polycation multilayers on hydrophilic or hydrophobic surfaces

Structural aspects of polyanion and hydrophobically modified polycation multilayers on hydrophilic or hydrophobic surfaces

Superlyophilic Interfaces and Their Applications

Tunable structural color in organisms and photonic materials for design of bioinspired materials

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Structural Color in Porous, Superhydrophilic, and Self‐Cleaning SiO2/TiO2 Bragg Stacks

Cited by 239 publications

References 34 publications

Structural aspects of polyanion and hydrophobically modified polycation multilayers on hydrophilic or hydrophobic surfaces

Structural aspects of polyanion and hydrophobically modified polycation multilayers on hydrophilic or hydrophobic surfaces

Superlyophilic Interfaces and Their Applications

Tunable structural color in organisms and photonic materials for design of bioinspired materials

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Product

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Structural Color in Porous, Superhydrophilic, and Self‐Cleaning SiO₂/TiO₂ Bragg Stacks