The polymer precursor route has emerged as a viable alternative to conventional colloidal processing routes towards porous ceramics in the recent past. A wide variety of methods introducing porosity into polymer-derived ceramics have been explored. However, the generation of aligned or directed pores, suitable for applications involving permeation, separation, or catalysis, remains challenging. Solidification templating, also referred to as freeze-casting, is a method suitable for the generation of highly-ordered pore structures. In contrast to conventional freeze casting, typically employing aqueous suspensions of ceramic particles, solidification templating of liquid preceramic polymers is complex, in particular when the compounds of interest are prone to hydrolytic decomposition. As a consequence, completely new processing approaches are required.
In this work, we present a novel technique to prepare cellular polysilazane-derived silicon carbonitride ceramics by combining non-aqueous solidification templating with a low-temperature photo-induced click reaction. This allows us to circumvent hydrolytic decomposition of water-sensitive precursor compounds such as polysilazanes while having access to unique advantages of the freeze-casting technique. In-depth investigations of the effect of process parameters during the solidification and polymerization sequence, in addition to the choice of template, facilitate the generation of cellular polymer-derived non-oxide ceramics with highly variable, tailorable pore structures, with prospective uses in a wide range of industrial processes.