Monolithic SiOC Ceramics with Tailored Porosity

A Direct Method for the Fabrication of Macro‐Porous SiOC Ceramics from Preceramic Polymers

“…The specimens possessed a quite complex morphology, as was the case for samples obtained using a similar fabrication procedure which were investigated in previous studies. [9,10] In addition to large cells of a few hundred microns in size (up to about 600 lm), a large amount of smaller, micron sized pores (∼ 5 lm) and cavities were present. Interestingly, the increase in the PDMS amount in the blends did not seem to significantly affect the mean pore size for both systems (PMS and PMPS).…”

“…[8] In recent years, it has been shown that blending preceramic polymers with different characteristics (molecular weight, molecular architecture, ceramic yield) allows to produce cellular ceramics. [9,10] This paper further explores this possibility, with the specific aim of directly developing a large amount of porosity within the resulting ceramic body during a one-step pyrolysis treatment.…”

Phase separation induced macroporous SiOC ceramics derived from polysiloxane

“…It decomposes to cyclic and linear dimethylsiloxane oligomers and completely escapes from the matrix at intermediate temperature during pyrolysis (above 400 • C) which avoids introducing other elements or impurities into the SiOC ceramics. PDMS, intrinsic or modified, has been added into sol-gel precursors, 20 PSO oils and/or resins [21][22][23][24] at high proportions (>40 wt.%) to fabricate meso-and macroporous SiOC with high surface area. However, little attention has been paid to design tailorable porous SiOC for different requirements and application utilizing the phase separation of PDMS.…”

Engineering porosity in polymer-derived ceramics

“…Alternative processing methods for the production of open or closed cell (macro-)porous ceramics have also been proposed by different researchers as well. These include the infiltration of a porous salt preform using a molten preceramic polymer, 34 coating of a polyurethane foam with a preceramic polymer, 35,36 evaporation of silane oligomers, 37 decomposition of a siloxane polymer during pyrolysis, 38 self-foaming by in situ evaporation of volatile condensation products generated during silicone crosslinking reactions, 39 foaming of a molten silicone by thermal decomposition of a solid blowing agent, 40 the dissolution of CO 2 gas into a preceramic polymer under pressure followed by introducing of a thermodynamical instability, 40-44 the use of expandable sacrificial polymeric microspheres, 5,45-47 the use of already expanded sacrificial polymeric microspheres, 48-50 the infiltration and pyrolysis of organic porous templates (wood structures), 51 the dissolution of colloidal silica sub-micron spheres, 52,53 or freeze-drying using camphene. 54 Moreover, several papers have been published dealing with the use of preceramic polymers to fabricate porous membranes (see for instance 55 and references therein), with pores sizes in the micro-and meso-range, and very recently the preparation of meso-porous ceramics via self-assembly of a preceramic polymer, 56 or via infiltration into meso-porous templates, 57,58 or via synthesis of an inorganic-organic diblock copolymer 59 has been reported.…”