Formation and Pore Structure of Boron Nitride Aerogels

Abstract

Gels containing a poly(boraziny1 amine) and tetrahydrofuran were processed by C 0 2 supercritical drying techniques followed by pyrolysis. The resulting BN ceramic aerogels are highly porous, and the microstructure, porosity, and surface area characteristics have been examined. The aerogels show excellent thermal stability exhibiting surface areas in excess of 350 m'/g and porosities greater than 0.8 even when heated in argon at 1500°C for 8 h. By removing solvent via evaporation before supercritical drying, the mean pore radius can be varied between 3.6 and 10 nm.

Catalytic ammonolytic sol–gel preparation of a mesoporous silicon aluminium nitride from a single-source precursor

“…In this paper, we will report the preparation of a new highsurface-area mesoporous silicon aluminum nitride with a high aluminum to silicon ratio via a non-aqueous ammonolytic sol-gel process using tetrakis(isopropylimino)bis[tris(dimethylamino)silylamino]alane H 6 Al 6 (N i Pr) 4 [NSi(NMe 2 ) 3 ] 2 , as a single-source precursor. The cage complex H 6 Al 6 (N i Pr) 4 [NSi(NMe 2 ) 3 ] 2 was prepared in our group by reaction of TDSA with poly(isopropyliminoalane) (HAlN i Pr) 6 [49].…”

“…The sol-gel technique is an attractive approach for preparing micro/ mesoporous oxide materials as powders, membranes and filters with high purity and homogeneity due to its flexibility and low temperature preparation of sols and gels [3]. A number of sol-gel processes to prepare highly porous nonoxide ceramics have also been reported, e.g., boron nitride [4][5][6][7][8], metal (carbo)nitrides [9][10][11][12][13][14], silicon carbonitride [15][16][17][18][19][20][21] and boron carbonitride [22,23]. A sol-gel process in an ammono-system has been used to prepare polymeric boron-, titano-and tantalo-silazanes by controlled co-ammonolysis of the elemental alkylamides [24].…”

Anisotropic Hexagonal Boron Nitride Nanomaterials: Synthesis and Applications

“…BNNTs grow from these sites; the diameter of the nanotubes depends on particles' sizes [64]. utilized to produce various forms of nanostructured BN [68,69]. Alumina anodic membrane (AAM) was used to synthesize 1D nanostructures due to its tunable pore dimensions, narrow pore-size distribution, and good mechanical and thermal-stability [70].…”

“…BN aerogels formed by critical point drying of poly(2,4,6-borazinylamine) gels and heated to 1000 ºC exhibit low density, are highly porous, and have surface areas of ~400 m 2 /g [69]. Porous BN materials with surface areas of 437-712 m 2 /g also were generated using similar polymeric precursors [114][115][116].…”

Carbon aerogel evolution: Allotrope, graphene-inspired, and 3D-printed aerogels

“…It has a similar structure to graphene except that the carbon atoms are replaced by alternating boron and nitrogen atoms. The first example of a BN aerogel was reported by Lindquist et al 112 in which a poly(borazinyl amine) aerogel is used as the precursor aerogel. This precursor aerogel is annealed up to 1200°C in ammonia, and then up to 1500°C in argon to produce turbostratic BN aerogels.…”