Methylamino Borazine Research Articles

Influence of the thermal process of carbon template removal in the mesoporous boron nitride synthesis

Influence of the thermal process involved in the carbon template elimination during the synthesis of mesoporous boron nitride by using nanocasting process of a mesoporous CMK-3 carbon with a borazinic precursor is presented. The borazinic precursor, the tri(methylamino)borazine (MAB), is converted to boron nitride (BN) inside the mesopores of a CMK-3 mesoporous carbon template by ceramization under nitrogen or under ammonia. The carbon template elimination is carried out by thermal treatment under air or under ammonia. The X-ray diffraction, TEM and pore size analysis are used to study the texture of the boron nitride synthesized from the carbon template. A template elimination performed by hydrogenation with an ammonia treatment allows to obtain an organized porous structure, which is not possible by using an oxidation treatment. In order to preserve the mesoporous organization of boron nitride, a two steps procedure (ceramization followed with template elimination by hydrogenation) is more efficient than a one step procedure (ceramization and template hydrogenation simultaneously).

Condensation of borazinic precursors for mesoporous boron nitride synthesis by carbon nanocasting

The influence of different borazinic precursors on mesoporous boron nitride synthesis by using a nanocasting process of a mesoporous CMK-3 carbon is presented. Two borazinic precursors, the tri(methylamino)borazine (MAB) and the tri(chloro)borazine (TCB), have been converted to boron nitride (BN) inside the mesopores of a CMK-3 carbon mesoporous template by using thermal or chemical polycondensation processes. Ordered mesoporous boron nitride with a specific surface area around 800 m2/g, a mesoporous volume around 0.6 cm3/g, and a pore-size distribution located at 6 nm in diameter was synthesized by thermal condensation of a molecular MAB precursor. In addition, chemical condensation of TCB led to a disordered mesoporous boron nitride.

Synthesis of boron nitride with a cubic mesostructure

The synthesis of mesoporous boron nitride by using tri(methylamino)borazine (MAB) as boron nitride source and a cubic mesoporous carbon (CMK-8) as template is described. The X-ray diffraction, TEM and pore size analysis show that the structure of the mesoporous BN consists in a 3D cubic array of uniform mesopores of 4.7 nm in diameter.

Synthesis conditions of ordered mesostructured boron nitride prepared from borazinic precursors and CMK-3 carbon template

AbstractThe preparation of ordered mesoporous boron nitride by using borazinic precursors as boron nitride source (tri(methylamino)borazine (MAB) and tri(chloro)borazine TCB) and a mesoporous carbon CMK-3 as template is reported. A template elimination performed by hydrogenation allows to obtain an organized porous structure. The X-ray diffraction, TEM and pore size analysis show that the structure of the BN molecular sieves synthesized from CMK-3 consists in a 2D regular array of uniform mesopores of 3.4 nm in diameter.

High-performance boron-nitride fibers from poly(borazine) preceramics

Boron-nitride (BN) fiber has been fabricated by utilizing the preceramic method. A melt-processable polymer precursor, poly(aminoborazinyl), was readily prepared by thermal condensation of B,B,B-tri(methylamino)borazine (MAB) in the presence of 10 wt% of 1-aminododecane (LA). It was melt-spun into thin fiber with an ordinary ram extruder. The spinnability of the fiber was excellent, in spite of the low molecular weight ( c. 570) of the precursor, because it has a structural similarity with melt-spinnable carbon pitch. On spinning the fiber surface was slightly hydrolyzed in atmosphere and the fiber became infusible. The fiber was then directly pyrolyzed up to 1000°C in an ammonia gas flow and was further sintered up to 1800°C in a nitrogen flow. The strength of the sintered BN fiber was found to increase above 1400°C and to reach 1 GPa at 1800°C. It was therefore confirmed that the BN fiber is free from the serious degradation above 1400°C in inert atmosphere where most of the common ceramic fibers are known to lose their original strength.