Highly Polarized Luminescence from Optical Quality Films of a Semiconducting Polymer Aligned within Oriented Mesoporous Silica

Molenkamp, William C.; Watanabe, Masatoshi; Miyata, Hirokatsu; Tolbert, Sarah H.

doi:10.1021/ja039296+

Cited by 176 publications

(134 citation statements)

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“…For example, Miyata and Tolbert et al reported alignment control of semiconducting polymers using uniaxially aligned mesoporous silica films. 25), 26) The semiconducting polymer was well aligned along the uniaxial mesochannels. The polymer/silica composite film showed the polarized absorption and fluorescence caused by aligned polymers.…”

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confidence: 99%

Field-Induced alignment controls of one-dimensional mesochannels in mesoporous materials

Yamauchi

2013

J. Ceram. Soc. Japan

147

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Mesoporous materials prepared through the self-assembly of surfactants have attracted wide attention because of their many potential applications. The mesostructural, compositional, and morphological controls of mesoporous materials have been extensively studied thus far. In particular, the macroscopic alignments of one-dimensional (1D) mesochannels and their controls are quite important for the creation of advanced functional materials. In most cases, the direction of mesochannels in mesoporous films lies parallel to the substrate. Vertical orientation of the mesochannels can realize high diffusion and accessibility of guest species from the outside. Here, I review the recent progress on this emerging research field. Various methods have been proposed for the preparation of vertically oriented mesoporous thin films using high magnetic field, shear flow, modification of the substrate, and other methods. I also briefly introduce their applications and a perspective for the future.©2013 The Ceramic Society of Japan. All rights reserved.Key-words : Mesoporous material, Surfactant, Thin film, High magnetic processing [Received April 25, 2013; Accepted June 23, 2013] 1. Mesoporous materials by self-assembly of surfactants Ordered mesoporous materials prepared through 'self-assembly of surfactants' have attracted growing interest due to their special properties, including uniform mesopores (250 nm) and high specific surface areas. 1),2) According to the International Union of Pure and Applied Chemistry (IUPAC), porous materials are classified according to their pore sizes: microporous materials with pore sizes below 2 nm, mesoporous materials with pore sizes between 2 and 50 nm, and macroporous materials with pore sizes exceeding 50 nm.3),4) Zeolites are traditional microporous materials that have been utilized for practical applications in catalysts and adsorbents. Although the microporous materials have high surface areas, due to their small-sized pores, their applications are limited to reactions only for relatively small molecules. Recently, metalorganic frameworks (MOFs) or porous coordination polymers (PCPs) consisting of metal ions coordinated with organic molecules have been extensively studied and used for the storage of gases such as hydrogen and carbon dioxide. 5),6) However, their pore size is still small. In contrast, several types of macroporous materials, such as inverse opal films, track-etched polycarbonate membranes, and porous anodic alumina membranes, have been reported thus far. However, such pore expansion seriously decreases surface area.Unlike other porous materials, mesoporous materials can be easily prepared under a wide range of synthetic conditions. Mesoporous materials exhibit several defined mesostructures, such as lamellar, two-dimensional (2D) hexagonal, three-dimensional (3D) hexagonal, and bicontinuous cubic mesostructures. Furthermore, many framework compositions (e.g., silica, organosilica, metal, and non-siliceous oxides) and various morphologies (e.g., nanoparticle, monolith, a...

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confidence: 99%

Field-Induced alignment controls of one-dimensional mesochannels in mesoporous materials

Yamauchi

2013

J. Ceram. Soc. Japan

147

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“…Tolbert et al also succeeded in alignment control of semiconducting polymers inside uniaxially aligned mesochannels. 460,461 The semiconducting polymer was aligned along the uniaxial mesospace, showing strong polarized absorption and fluorescence. Moreover, the confinement leads to low-threshold amplified spontaneous emission from the aligned polymer chains.…”

Section: Mesoporous Non-siliceous Filmsmentioning

confidence: 99%

Nanoarchitectonics for Mesoporous Materials

Ariga

Vinu

Yamauchi

et al. 2011

Bulletin of the Chemical Society of Japan

716

411

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Although mesoporous materials have well-defined pore structures, these fine materials can surprisingly be produced by employing a set of conventional and simple procedures such as mixing, heating, filtration, and washing, using low-cost materials. They can be regarded as easy-to-make bulk nanostructured materials. Mesoporous materials have great potential for use in both macroscopic applications and nanotechnology. In this account, we introduce examples of recent developments in mesoporous materials involving innovations in their components and structural designs and concentrating on our own recent progress. These examples include syntheses of mesoporous silica, metal oxides, semiconductive materials, metals, alloys, organic composites, biomaterial composites, carbon, carbon nitride, and boron nitride, as innovative components. As structural innovations for mesoporous materials, various film preparations, pore alignments, and hierarchic structures are described together with their related functions including sensing and controlled release of target molecules. Why Mesoporous Materials? Bulk Quantities and Precise StructuresThere is little doubt that nanotechnology and related technologies are making significant contributions to current research and development which will eventually be felt in our day-to-day lives. Device miniaturization in such products as cellular phones and portable computers has irrevocably changed our lifestyles. Portable devices allow us to work and communicate wherever we are in the world in contrast to the previous situation where machine operation required a human presence. Greater freedom in our work and leisure dispositions should diminish over-concentration of populations in cities and may ultimately reduce energy consumption and waste production.So far, device innovations have been due to development of top-down approaches, especially sophisticated microfabrication techniques. 17 However, those top-down techniques are not useful for materials innovation where chemical processes are used as the operating principle. Rather, so-called bottom-up approaches are expected to create novel functional materials having well-controlled structural features with nanometric precision. Bottom-up approaches rely on self-assembly processes to form selected structures through spontaneous association of atoms, molecules, clusters, and particles. 818 Furthermore, assisted assembly techniques using external influences are provided by LangmuirBlodgett (LB) method 1928 and layer-by-layer (LbL) adsorption 2936 and provide significant contributions for materials' fabrication. According to these concepts, molecular complex formation, 3741 molecular array control, 4252 and microscopic structural design 5361 have been widely investigated leading to generation of a large quantity of scientific knowledge.Ideally, materials should be produced in a series of easy processes to yield bulk quantity without loss of nanometric structural features and some categories of material already satisfy this condition. For exampl...

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“…This is probably caused by the weaker hydrophobic interaction of C 10 EO 10 and C 12 EO 10 with the rubbing-treated polyimide surface due to their shorter alkyl chains. 8 To find optimum synthetic conditions of the films with the aligned mesochannels, we performed a systematic analysis of the ª2ª XRD profiles. We subtracted the profile recorded under the geometry in which the X-rays were parallel to the rubbing direction from that recorded under the perpendicular geometry, in order to extract the anisotropy of the diffraction peaks.…”

Section: ¹1mentioning

confidence: 99%

“…8,9 Several methods to control the alignment of the mesochannels have been reported. 1017 Among them, the method in our previous report using a substrate with a rubbing-treated polyimide layer combined with evaporation-induced self-assembly (EISA) can control the mesochannel direction within the º distribution of 3°at macroscopic scales.…”

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confidence: 99%

“…15 Especially, MPS films with highly aligned cylindrical mesochannels are expected to be used for anisotropic accommodation of various guest species, e.g., metals, 6 dyes, 7 and polymers. 8,9 Several methods to control the alignment of the mesochannels have been reported. 1017 Among them, the method in our previous report using a substrate with a rubbing-treated polyimide layer combined with evaporation-induced self-assembly (EISA) can control the mesochannel direction within the º distribution of 3°at macroscopic scales.…”

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Control of Periodicity in Mesoporous Silica Films with Aligned Mesochannels Prepared by a Sol–Gel Process

2012

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Periodicity of mesoporous silica films with aligned cylindrical pores formed on a substrate with a rubbing-treated polyimide through a solgel process can be finely controlled using nonionic surfactants with different alkyl chains. The degree of alignment increases with the alkyl-chain length of the surfactant due to increase in anisotropic hydrophobic interaction between the oriented polyimide chains and the alkyl groups, which is responsible for the alignment.Mesoporous silica (MPS) films are promising materials for application in optical and electronic molecular devices because they have highly ordered nanostructures and are synthesized through a simple self-assembly process.15 Especially, MPS films with highly aligned cylindrical mesochannels are expected to be used for anisotropic accommodation of various guest species, e.g., metals, 6 dyes, 7 and polymers. 8,9 Several methods to control the alignment of the mesochannels have been reported. 1017 Among them, the method in our previous report using a substrate with a rubbing-treated polyimide layer combined with evaporation-induced self-assembly (EISA) can control the mesochannel direction within the º distribution of 3°at macroscopic scales.11 The method, however, has not achieved to control the periodicity of the MPS films, which associates with the pore size. The optimum conditions for the preparation of aligned MPS films using different surfactants have been difficult to find because it is necessary to take the interactions between the oriented polyimide chains and the surfactant molecules into account in addition to the self-assembly of the surfactant. The control of the pore size of the aligned mesochannels enables the fine tuning of the properties of the guest species in the mesochannel through changes of the amount and the conformation. In view of this situation, we report the control of the periodicity and the pore size of the MPS films with aligned mesochannels by varying alkyl-chain length of nonionic surfactants.The MPS films with the aligned mesochannels were prepared based on our previous method 11 after careful optimization for each surfactant. The polyimide with a 8-nm thickness on a Si wafer underwent rubbing treatment using a cottoncovered cylindrical roller. Nonionic surfactant (poly(oxyethylene)-10-alkyl ether, C n EO 10 , n = 10, 12, and 16) was dissolved in 2-propanol (IPA), and then ultrapure water (Milli-Q), 0.1 M HCl, and tetraethoxysilane (TEOS) were added to the solution. The final molar ratio of the chemicals was C n EO 10 8.00 © 10 ¹2 0.120/TEOS 1.00/IPA 16.7/H 2 O 5.00/HCl 4.00 © 10 ¹3. After stirring and aging the solution for 0.53.0 h, the Si wafer was dip-coated with the solution at withdrawal speed of 1.5 mm s ¹1 at 25°C and 3943% RH and subsequently dried at 25°C and 40% RH over 16 h. The surfactants were removed by calcination at 400°C for 10 h in air. Structural analysis of the synthesized films was performed by X-ray diffractometry (XRD). Conventional ª2ª scanning XRD and in-plane XRD were performed with Philips X'Pert Pr...

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Highly Polarized Luminescence from Optical Quality Films of a Semiconducting Polymer Aligned within Oriented Mesoporous Silica

Cited by 176 publications

References 22 publications

Field-Induced alignment controls of one-dimensional mesochannels in mesoporous materials

Field-Induced alignment controls of one-dimensional mesochannels in mesoporous materials

Nanoarchitectonics for Mesoporous Materials

Control of Periodicity in Mesoporous Silica Films with Aligned Mesochannels Prepared by a Sol–Gel Process

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