Ordered mesoporous crystalline aluminas from self-assembly of ABC triblock terpolymer–butanol–alumina sols

Abstract

A one-pot synthesis approach is described to generate ordered mesoporous crystalline g-alumina-carbon composites and ordered mesoporous crystalline g-alumina materials via the combination of soft and hardtemplating chemistries using block copolymers as soft structure-directing agents. Periodically ordered alumina hybrid mesostructures were generated by self-assembly of a poly(isoprene)-block-poly(styrene)-block-poly(ethylene oxide) terpolymer, n-butanol and aluminum tri-sec-butoxide derived sols in organic solvents. The triblock terpolymer was converted into a rigid carbon framework during thermal annealing under nitrogen to support and preserve the ordered mesoporous crystalline g-alumina-carbon composite structures up to 1200 C. The carbon matrix was subsequently removed in a second heat treatment in air to obtain ordered mesoporous crystalline g-alumina structures. Such thermally stable, highly crystalline, and periodically ordered mesoporous ceramic and ceramic-carbon composite materials may be promising candidates for various high temperature catalysis, separation, and energyrelated applications.

Nanocrystalline carbon coated alumina with enhanced phase stability at high temperatures

“…19,23 Earlier we have reported that the carbon coating deposited on the surface of the oxide nanoparticles can act as a nanoreactor shell. On the one hand, such coating can be penetrable for the reactant molecules from the gas 7,10,24,25 or liquid 26 phases making it possible to initiate various catalytic or solid-state reactions inside the nanoreactor. Moreover, the carbon coating prevents sintering of nanoparticles inside the shell during the temperature increase and stabilizes their sizes.…”

Ultrafast Crystallization of Ordered Mesoporous Metal Oxides and Carbon in Seconds

“…Highly crystalline, ordered mesoporous oxide and carbon materials generated by structuredirecting surfactants and block copolymers (BCPs) are desirable for their tunable periodic morphologies and multifunctional properties, [1][2][3][4][5][6][7] and have been widely deployed in many applications 8 ranging from catalysis, 9,10 energy conversion and storage, [11][12][13][14] adsorption and separation, 15,16 sensing 17,18 and even superconductors. 19 However, conventional routes to form mesoporous inorganic structures with high crystallinity typically require thermal annealing treatments at elevated temperatures (≥600 °C) over long durations (≥10 hours) under controlled environments (e.g., argon, ammonia) for inorganic crystallization, thereby increasing production time and cost.…”

“…19 However, conventional routes to form mesoporous inorganic structures with high crystallinity typically require thermal annealing treatments at elevated temperatures (≥600 °C) over long durations (≥10 hours) under controlled environments (e.g., argon, ammonia) for inorganic crystallization, thereby increasing production time and cost. [3][4][5][6][7][15][16][17][18][19] In particular, untamed nucleation and growth of crystallites that occur spontaneously at higher temperatures often result in the collapse of ordered structures. 2,5,7 Alternative nonequilibrium methods have been explored for the rapid formation of single crystal and polycrystalline inorganic nanostructures on shorter time frames.…”

“…[3][4][5][6][7][15][16][17][18][19] In particular, untamed nucleation and growth of crystallites that occur spontaneously at higher temperatures often result in the collapse of ordered structures. 2,5,7 Alternative nonequilibrium methods have been explored for the rapid formation of single crystal and polycrystalline inorganic nanostructures on shorter time frames. [20][21][22][23][24][25][26][27][28][29] For example, Tan et al demonstrated an all-laser-induced approach coupling BCP-directed self-assembly of resols with sub-millisecond laser heating (B-WRITE) to write hierarchically mesoporous polymer and carbon thin film structures.…”

Ordered crystalline mesoporous γ-alumina fabricated by vacuum-promoted self-assembly and alkaline hydrothermal method

“…However, the practical application is plagued by the poor thermal stability resulted from their amorphous or semi-crystalline pore walls. As a result, design and synthesis of MA with crystalline pore walls has long been a hot topic [5][6][7][8]. Recently, considerable efforts [9][10][11][12] have been devoted to reduce the synthesis cost of crystalline MA by using the inexpensive inorganic aluminum salts to replace aluminum alkoxides.…”