Triblock copolymer templated

Apparent advantage of the prefabricated nanoparticles hes in the opportunity to use well-developed procedures to control particle size and particle size distribution and to characterize the particles by all possible means. Prefabricated particles can be introduced in the mesoporous materials in two ways. One avenue is direct incorporation of particles in sol-gel mixture as was recently reported in [60]. Here mesostructured nanoparticle-sihca monoliths have been synthesized by dispersing prefabricated Au or zeohte (sihcate) nanoparticles in sol-gel precursors containing SiCl4 and a Pluronic triblock copolymer template. To improve the compatibility of the Au nanoparticles with the poly(ethylene oxide) block, the nanoparticle surface was modified with a SiOj layer. Therefore, this technique requires good compatibihty of nanoparticles with the components of the sol-gel reaction, as it influences the distribution of nanoparticles through the material. Another hmitation of this method is encapsulation of particles within mesoporous material, but not necessary location in the pores. As was discussed above, this limitation is especially crucial for catalytic applications. 

Shi ZT, Pan DY, Zhao SF et al (2006) Self-assembly of ordered silver nanoparticle chains on triblock copolymer templates. Mod Phys Lett B 20(20) 1261-1266... 

Even milder conditions for template removal can be achieved using supercritical fluids, such as carbon dioxide. " Treatment with supercritical CO2 alone is effective only in removing triblock copolymer templates from templated silicates, however inclusion of an alcohol improves the extraction efficiency for ionic surfactant templates.Washing with methanol modified supercritical CO2 was shown to remove 76-95 % of the surfactant template from MCM-41 and MCM-48 films, powders and SBA-1, SBA-3 powders at 85 Other groups prefer supercritical... 

Further evidence for phase separation driven co-assembly was found by Flodstrom et in work on triblock copolymer templated... 

The effect of addition of NaCl to a nonionic triblock copolymer templated silica synthesis was investigated by Alfredsson et who showed that NaCl made the aqueous solution more polar and thus a worse solvent... 

Figure 2.16 Typical nitrogen adsorption-desorption isotherms at 77K for (a) MCM-41 materials templated with alkyltrimethylammonium bromide surfactants with hydrophobic tails of different lengths as indicated (volumes adsorbed for C12, C14, C16 and C18 were incremented by 200, 400, 600 and 800 ml(STP) g, respectively) and (b) nonionic triblock copolymer templated SBA-15 silicas synthesised at different temperatures (volumes adsorbed for 353 K and 373 K were incremented by 200 and 400 ml(STP) respectively). The hysteresis loops observed in this case are typical of the larger mesopores in these materials. Desorption points are represented by closed symbols. Reprinted with permission from Morishige, K. Tateishi, M., Accurate relations between pore size and the pressure of capillary condensation and the evaporation of nitrogen in cylindrical pores, Langmuir, 22, 4165 169. Copyright (2006) American Chemical Society...

Wan Y, Qian X, Jia N, Wang Z, Li H, Zhao D (2008) Direct triblock-copolymer-templating synthesis of highly ordered fluorinated mesoporous carbon. Chem Mater 20 1012-1018... 

Solid State Dye-Sensitized Solar Cell, Fig. 4 Cross-sectional SEMs of (a) ZnO nanowires (Reprinted with permission from [62], Copyright 2012 American Chemical Society), (b) Triblock copolymer templated photoanodes (Reprinted with permission from [55], Copyright 2012 WILEY-VCH Verlag GmbH Co. KGaA,... 

Yao N., Ku A.Y., Nakagawa N., Lee T., SavUle D.A., Aksay I.A. Disorder-order transition in mesoscopic silica thin films. Chem. Mater. 2000 12 1536-1548 Yun H.-S., Miyazawa K., Zhou H., Honma I., Kuwabara M. Synthesis of mesoporous thin Ti02 films with hexagonal pore structures using triblock copolymer templates. Adv. Mater. 2001 13 1377-1380... 

Aizawa, M. and Buriak, J.M. (2006) Nanoscale patterning of two metals on silicon surfaces using an ABC triblock copolymer template. Journal of the American Chemical Society, 128(17), 5877-5886. 

Tanaka S, Doi A, Nakatani N, Katayama Y, Miyake Y (2009) Synthesis of ordered mesoporous carbon films, powders, and fibers by direct triblock-copolymer-templating method using an ethanol/water system. Carbon 47(ll) 2688-2698, http //dx.doi.Org/10.1016/j.carbon.2009.05. 024... 

The star-polymer template approach allows preparation of spherical nanocrystals. In the initial step, a star-like block copolymer nanoreactor was prepared, with a polyacrylic acid (PAA) inner block and an outer block of polystyrene. Then, the inner PAA block was infiltrated with the precursor for preparation of the desired nanoparticles. Finally, the precursor is transformed into the nanoparticle inside the star-polymer template, resulting in formation of uniform well-defined nanocrystals. By using a star-like triblock copolymer template, core-shell and hollow nanocrystals can be prepared following similar strategies (Scheme 9). 

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