Evaluation of mechanical properties and hydrophobicity of room‐temperature, moisture‐curable polysilazane coatings

Polysilazane coatings have a broad need in real‐life applications, which require low processing or working temperature. In this work, five commercially available polysilazanes have been spin‐coated on polycarbonate substrates and cured in ambient environment and temperature to obtain transparent, crack‐free, and dense films. The degree of crosslinking is found to have a significant impact on the hardness and Young's modulus of the polysilazane films but has a minor influence on the film thickness and hydrophobicity. Among all five polysilazane coatings, the inorganic perhydropolysilazane‐based coating exhibits the largest hardness (2.05 ± 0.01 GPa) and Young's modulus (10.76 ± 0.03 GPa) after 7 days of curing, while the polyorganosilazane‐derived films exhibit higher hydrophobicity. The molecular structure of polysilazanes plays a key role in mechanical properties and hydrophobicity of the associated films, as well as the adhesion of coatings to substrates, providing an intuitive and reliable way for selecting a suitable polysilazane coating material for a specific application.