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A new processing approach combining solidification templating of initially liquid preceramic polymers with a low-temperature, photoinduced crosslinking step based on a thiol-ene click reaction was recently introduced, allowing for the generation of porous polysilazane-derived ceramics with directionally aligned pore channels. In this work, the focus is set on investigating the roles of the type of structure-directing solvent, the addition of nucleating agents, and the initial precursor content on the resulting porosity, pore morphology, and properties of ceramics generated through this technique. The variation of the structure-directing solvent facilitates the generation of various pore channel morphologies, ranging from dendritic to lamellar and columnar structures. The generated materials are evaluated with regard to gas permeability and compressive strength. Depending on the processing parameters, porosity between 40% and 78% is achieved, with median pore opening sizes ranging from 7 to 70 μm. Consequently, a large range of gas permeability (3 Á 10 À13 m 2 to 1 Á 10 À10 m 2 ) and compressive strength values (0.7 to 51 MPa) are observed. The results show that photopolymerization-assisted solidification templating of preceramic polymers is indeed a robust technique for a wide parameter range, allowing for the generation of well-tailored pore structures for various prospective fields of application.

A processing technique for the preparation of porous, silicon carbonitride-based ceramics in tubular geometry derived from a liquid polysilazane precursor is presented. After casting of polysilazane/polymer-microbead dispersions, cross-linking, and subsequent pyrolytic conversion and selective removal of polymer templates, specimens with an inner and outer diameter of 6 and 10 mm, respectively, and a length of up to 65 mm were obtained. Porosity was controlled by sacrificial template content and reached values up to 48% after pyrolytic conversion, at average pore opening radii of 1¯m. The tubular specimens exhibited diametral compression strengths (C-ring test) between 24 « 6 and 36 « 4 MPa. Darcian permeability constants of up to 1.7·10 ¹14 m 2 were found by gas permeability testing. The results demonstrate that this methodology facilitates the straightforward generation of complex-shaped porous specimens, further allowing for a control of strength and permeability in a specific range. Potential applications for the tubular, porous structures developed can be anticipated in the fields of separation or catalysis.

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