Ordered Mesoporous Silicoboron Carbonitride Materials via Preceramic Polymer Nanocasting

Highly ordered two-dimensional (2D) mesoporous silicoboron carbonitride (SiBCN) materials were prepared by a double nanocasting approach using mesoporous SBA-15 silica as starting template. The latter was converted into its negative replica CMK-3 carbon template, which was subsequently impregnated with a boron-modified polysilazanes of the type [B(C 2 H 4 SiCH 3 NCH 3 ) 3 ] n ([C 14.4 H 31.4 N 4.1 B 1.0 Si 3.0 ] n ) using a liquid-phase impregnation (LPI) process. The derived [B(C 2 H 4 SiCH 3 NCH 3 ) 3 ] n -carbon composite was cross-linked under ammonia at 200 °C and then thermolyzed under nitrogen at 1000 °C to generate a SiBCN-carbon composite. The carbon template was subsequently removed through thermal treatment at 1000 °C in an ammonia atmosphere to generate ordered mesoporous structures. XRD and TEM analyses revealed that as a negative replica of the CMK-3 template, the obtained amorphous mesoporous material exhibited open, continuous, and ordered 2D hexagonal frameworks, whereas elemental analyses indicated the formation of materials with an empirical formula of Si 3.0 B 1.0 C 4.2 N 3.5 . The ordered mesoporous Si 3.0 B 1.0 C 4.2 N 3.5 material displayed high surface area (600 m 2 g −1 ), high pore volume (0.61 cm 3 g −1 ), and narrow pore size distribution (around 3.4 nm) and exhibited a relatively good thermal stability in air through heat-treatment to 1400 °C.