Monolithic silicon carbide with interconnected and hierarchical pores fabricated by reaction‐induced phase separation

Abstract Hierarchically porous silicon carbide (SiC) monoliths were fabricated based on polycarbosilane ( PCS ), divinyl benzene ( DVB ), and decalin, by a sequence of procedures including catalyst‐free hydrosilylation reaction‐induced phase separation, ambient‐pressure drying, calcination, and HF etching. The influences of ratios of each component on the phase separation were systematically studied. It was found that isotactic polypropylene added as a nonreactive additive could effectively tailor the microstructure and improve the mechanical properties of SiC monoliths. The resultant SiC monoliths mainly consisted of β‐SiC nanocrystals, and possessed low bulk density (0.7 g/cm 3 ), high porosity (78%), large specific area (100.6 m 2 /g), high compressive strength (13.5 ± 1.6 MPa), and hierarchical pores (macropores around 350 nm, mesopores around 4 and 20 nm). These properties make SiC monoliths promising materials for catalyst/catalyst support, gas separator, and the reinforcement of high‐temperature composites.