Synthesis of Liquid Polysilazoxanes for SiOCN Ceramics With Adjustable Composition and High‐Temperature Properties

ABSTRACT Preparing polysilazoxanes with a controlled molecular structure is the ideal route for fabricating SiOCN ceramics with adjustable composition and properties. In this paper, liquid polysilazoxanes were synthesized via a controlled substitution reaction between trichlorosilane and alcohols (ROH), followed by the condensation with ammonia. By adjusting the alkyl groups (R tert ‐butyl, dioxane and triazolylmethyl) of alcohols, three kinds of polysilazoxanes with SiNSi backbones, but different side chains were synthesized. During high‐temperature pyrolysis, tert ‐butoxy groups in polysilazoxanes are easily removed, producing low‐carbon (< 4 wt%) ceramics, while dioxane and triazolylmethyl groups decompose to form oxygen‐rich and nitrogen‐rich ceramics, respectively. Due to the composition distinction, the resulting SiOCN ceramics showed quite different high‐temperature behavior. This report provides a direct and effective method for obtaining polysilazoxanes with a controlled molecular structure, which is useful for fabricating SiOCN ceramics with improved high‐temperature performance.