Thermally induced borazine dehydropolymerization reactions. Synthesis and ceramic conversion reactions of a new high-yield polymeric precursor to boron nitride

Amineborane Based Chemical Hydrogen Storage - Final Report

“…On the other hand, the in situ NMR studies of the AB/bmimOTf reactions, as well as similar NMR studies of the 85 o C H 2 -release from AB/mmimMeSO 4 and AB/bmimI reactions, showed the growth of a 16 ppm resonance after the release of 2 H 2 -equiv. The 16 ppm resonance in these ionic liquid reactions is thus shifted almost 14 ppm upfield relative to that normally found for polyborazylene [39][40][41] or borazine. 42 This suggests that if either of these unsaturated species were formed in these solutions, the observed chemical shift change could result from interactions with the ionic liquid solvent. )…”

“…The solid-state 11 B NMR spectra (Figures 5.12 and 5.13) of the insoluble AB spent-fuel products of the metal-catalyzed H 2 -release in ionic liquids were similar to those obtained from the uncatalyzed reactions with each spectrum exhibiting a broad downfield resonance characteristic of cross-linked polyborazylene structures. [39][40][41] Thus, even though the uncatalyzed and metal-catalyzed AB H 2 -release reactions in ionic liquids appear to go by different mechanistic pathways and intermediate species, both reactions ultimately produce similar spent fuel materials composed of an sp 2 boron-nitrogen framework with B=N units. …”

“…Consistent with the faster H 2 -release found for the PS/AB mixtures, the spectra show that after 22 h the amount of unreacted AB was less in the PS/AB reactions than in that of the pure AB reaction. The solid-state 11 B NMR spectra in Figure 4.5 of the final products of the reactions showed an additional broad resonance centered near ~23 ppm that is characteristic of the sp 2 boron-framework of cross-linked polyborazylene structures, [39][40][41] thus indicating that AB dehydrogenation ultimately produces B=N unsaturated products.…”

“…The solid-state 11 B NMR spectrum of the final product after the release of 2 H 2 -equiv. showed a broad downfield resonance characteristic of the sp 2 boron-nitrogen framework of cross-linked polyborazylene structures, [39][40][41] indicating that AB dehydrogenation ultimately produced B=N unsaturated products. NMR studies of the dehydrogenated products of AB H 2 -release promoted by solid-state thermal reactions 7,40 have likewise shown the formation of B=N unsaturated final products after the release of more than 2 H 2 -equiv.…”

Anisotropic Hexagonal Boron Nitride Nanomaterials: Synthesis and Applications

“…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]. Borazine (B 3 N 3 H 6 ) is proved to be an almost ideal precursor because of its high ceramic yield to BN, no carbon content, and easy change to BN upon thermal treatment without NH 3 [71]. Other well-known good precursors are polyvinylpentaborane, polyvinylborazine, and dibromoboranedimethyl sulphide for forming BN upon ammonia thermolysis.…”