Chemically derived BN ceramics:: Extensive 11B and 15N solid-state NMR study of a preceramic polyborazilene

Polyborazilene, a precursor for hexagonal boron nitride (h-BN) ceramics, has been extensively characterized by N-15 and B-11 MAS NMR. The various B and N sites have been identified according to their first neighboring atoms as well as to the second ones in the case of N-15 and have also been quantified. This study demonstrates that a suitable choice of NMR techniques together with the use of isotopic enrichment can lead to a large improvement in spectral resolution, which allows better understanding of such complex BN preceramic polymer structures.