Influence of DVB as linker molecule on the micropore formation in polymer-derived SiCN ceramics

Abstract

In this work, the formation of transient microporosity during the polymer-to-ceramic conversion in polymer-derived ceramics was studied using a commercially available poly(vinyl)silazane precursor which was modified with divinylbenzene (DVB) as linker molecule during crosslinking. After pyrolysis treatments between 400 and 700 °C, the resulting materials not only showed distinct changes in elemental composition and structural features upon introduction of the linker molecule, but also a shift in micropore size, e.g. shifting from 0.84 nm to 0.70 nm after pyrolysis at 600 °C. Due to hindrance of transamination reactions in the low-temperature region, the nitrogen content in linker-containing samples was significantly higher, leading to a different composition of micropore-forming entities and, in case of the system studied, to smaller pores. These findings are a first step towards the clarification of the mechanisms leading to the pore formation in PDCs during pyrolytic conversion, which is essential for their use in prospective applications.