Ordered mesoporous polymer-derived ceramics and their processing into hierarchically porous boron nitride and silicoboron carbonitride monoliths

Inorganic porous materials are widely used in a number of applications, where there is a need to produce materials with a controlled and/or multiscale porosity. In this category, periodic mesoporous boron-and silicon-based non-oxide ceramic frameworks with P6mm hexagonal symmetry attract increasing interest due to their unique properties, functionalities and potential applications. These materials are prepared by a hard-templating route (= nanocasting) using ordered mesoporous templates including silica (SBA-15) and carbon (CMK-3). In the first part of this perspective, the synthesis approach of ordered mesoporous boron nitride (BN) and silicoboron carbonitride (Si-B-C-N) is emphatically described including precursor selection and synthesis, nanocasting process, pyrolysis and template removal. In order to satisfy the requirement for practical applications, the second part of this perspective describes how a convenient powder processing approach that adopts the flexibility of powder-based processes (spark plasma sintering (SPS)) has been employed to produce without the use of any sintering additives mechanically stable, hierarchically porous BN and Si-B-C-N monoliths from ordered mesoporous powders.