Preparation and performance study of low-surface-energy polysilazane coatings modified with short-chain perfluoroalcohols

Polysilazane ceramic precursor coatings have attracted great interest in the protective coatings field due to their excellent hardness, wear resistance, and chemical stability. However, their poor hydrophobicity limits their use in self-cleaning and anti-graffiti applications. Fluorination is an effective way to reduce surface energy, but long-chain fluorocarbon compounds are strictly regulated due to bioaccumulation and environmental persistence. The modification effects and structure–property relationships of short-chain alternatives remain unclear. In this study, short-chain perfluoroalcohols with different chain lengths (C4, C6) and structures (linear, branched) were used to modify polysilazane. The effects of fluorocarbon chain structure on coating wettability, mechanical properties, thermal stability, and anti-graffiti performance were systematically investigated. Fluorocarbon modification reduced the surface energy from 25.0 mN/m to 20.1–21.2 mN/m. Extending the chain length from C4 to C6 led to only a further reduction of 1.1 mN/m, showing a clear diminishing return effect. The difference between linear and branched structures was only 0.2 mN/m, suggesting that branched perfluoroalcohols are a viable alternative to linear ones. The modified coatings maintained a pencil hardness of 4H and withstood over 200 methyl ethyl ketone (MEK) double-rub cycles. Good thermal stability and excellent anti-graffiti performance were also achieved. This work confirms the feasibility of directly modifying polysilazane with short-chain perfluoroalcohols. It provides a theoretical basis and experimental foundation for developing protective coatings with both hydrophobicity and thermal resistance.