Photocalcination of Mesoporous Silica Films Using Vacuum Ultraviolet Light

Hozumi, Atsushi; Yokogawa, Yoshiyuki; Kameyama, Tetsuya; Hiraku, Katsumasa; Sugimura, Hiroyuki; Takai, Osamu; Okido, Masazumi

doi:10.1002/1521-4095(200006)12:13<985::aid-adma985>3.0.co;2-#

Cited by 88 publications

(56 citation statements)

References 19 publications

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“…Our approach departs from nonhydrolyzed precursor film and exploits UV light's versatility to drive both (i) self-assembly and (ii) subsequent surfactant degradation in a single and continuous stage. Note that these two photochemical reactions were already reported separately [9][10][11] but have never been combined together to form a single route relying on the same UV lamp. In this process, the role of UV light is twofold:…”

Section: Surfactant-directed Synthesis Of Mesoporous Films Made Singlmentioning

confidence: 99%

Surfactant-directed synthesis of mesoporous films made single-step by a tandem photosol-gel/photocalcination route

et al. 2014

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In view of their technological impact in materials chemistry, a simplified and more efficient synthetic route to mesoporous films is highly sought. We report, herein, a smart UV-mediated approach coupling in a one-stage process sol-gel photopolymerization and photoinduced template decomposition/ablation to making mesoporous silica films. Performed at room temperature with a solvent-free solution of silicate precursor and amphiphilic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer, the synthesis relies on photoacid generation to induce the fast formation (≈10 min) of mesostructured silica/surfactant domains. Continuation of UV exposure for three additional hours enables subsequent and complete photodegradation of the polyether copolymer, resulting in ordered or disordered mesoporous silica film. One of the most attractive features is that the one-step procedure relies on a continuous illumination provided by the same conventional medium-pressure Hg-Xe arc lamp equipped with a 254 nm reflector to enhance the emission of energetic photons <300 nm. In addition to X-ray diffraction and transmission electron microscopy, time-resolved Fourier transform infrared spectroscopy has proved to be a powerful in situ technique to probe the different chemical transformations accompanying irradiation. Photocalcination strengthens the inorganic network, while allowing to preserve a higher fraction of residual silanol groups compared with thermal calcination. A polyether chain degradation mechanism based on oxygen reactive species-mediated photo-oxidation is proposed.

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Section: Surfactant-directed Synthesis Of Mesoporous Films Made Singlmentioning

confidence: 99%

Surfactant-directed synthesis of mesoporous films made single-step by a tandem photosol-gel/photocalcination route

et al. 2014

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“…91 The surfactant molecules are generally removed by calcination by heating up to high temperatures exceeding 573 K. Here, photo-decomposition (photocalcination) by vacuum UV light achievable at room temperature is applied according to a modified method of Hozumi et al 93 It is expected that the distortion of the mesoporous structure in this method is more suppressed than that obtained via decomposition by heating.…”

Section: Photo-orientation Of Mesoporous Silica Filmmentioning

confidence: 99%

Dynamic Photoresponsive Functions in Organized Layer Systems Comprised of Azobenzene-containing Polymers

Seki

2004

Polym J

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ABSTRACT:Azobenzene (Az)-containing polymers provide fascinating photoresponsive actuation systems. When they are organized at interfaces, the motion of Az unit occurring at a molecular (sub-nano) scale can be transferred and amplified to larger scales of materials. This review article focuses to selected research topics on organized layer systems of Az-containing polymers proceeding in our laboratory. They involve i) photomechanical response of monolayers at nanometer levels in thickness and centimeters in area, ii) monolayer-mediated photoorientation of polymer (polysilane) and mesoporous silica at nano-to sub-micrometer levels in thickness, and iii) instant mass migration triggered by patterned photoirradiation occurring at distances over micrometer levels. In every system, strong cooperative interplays between the Az unit and organized molecular or macromolecular assemblies play the essential roles. Promotions of these research areas are anticipated to provide wide and new opportunities for material processing and creation of new classes of photofuncitional soft materials.

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“…Although photocalcination with UV light in a vacuum could eliminate the surfactant template from MTFs at lower temperatures, it requires special and expensive apparatus. [11] Solvent extraction is another effective method to resolve this problem, [12] but a subsequent high temperature treatment is required to eliminate chemisorbed water and esterification products. [8e,13] These limitations imply that the conventional inclusion process, in which two stepsÐsurfactant template removal and then incorporation of nanosized particles into pore channelsÐ are involved, is not suitable for MTFs.…”

mentioning

confidence: 99%