Phase separation induced macroporous SiOC ceramics derived from polysiloxane

Macroporous SiOC ceramics have been fabricated through crosslinking and pyrolysis of a two-component polysiloxane (PSO) precursor consisting polyhydrosiloxane (PHMS) and tetravinylcycletetrasiloxane (D4Vi) utilizing phase separation of linear polydimethylsiloxane (PDMS) in PSO. The crosslinking of PSO is initiated by Pt-catalyzed hydrosilylation between PHMS and D4Vi concurrently; and at the meantime phase separation also occurs, forming PSO-rich and PDMS-rich phases. The morphology of PDMS phase in the obtained PSO/PDMS gel can be easily tailored from isolated phase to continuous phase by tuning the initial PDMS concentration. Subsequent pyrolysis treatment yields macroporous SiOC ceramics in which pores arise from thermal depolymerization and evaporation of the PDMS phase. The obtained SiOC ceramics possess controllable morphologies with closed-pores structure, worm-like continuous structure or stacking-particulates structure, which perfectly resembles the morphology of respective PSO/PDMS gel.