Thin gas-barrier silica layers from perhydropolysilazane obtained through low temperature curings: A comparative study

Perhydropolysilazane (PHPS) conversion to silica through different low temperature routes has been studied. This study showed the influence of main conditions such as moisture and temperature on the conversion kinetics. Catalytic effects of ammonia both in solution and in the gas fraction and hydrogen peroxide were investigated. Possible conversion mechanisms in the presence of ammonia and peroxide catalysts are proposed, since both appear to play a significant role in the conversion of PHPS, although the effect is limited to the first conversion step. Barrier properties against water and oxygen shown by polymer films coated by thin inorganic layers obtained following these curing routes have then been compared using an innovative permeation measurement method. Oxygen and water permeability measurements show that the curing method has a noticeable effect on gas barrier efficiency. The most efficient barrier layers tested in this work led to a barrier improvement factor against oxygen of circa one order of magnitude.

► We synthesized thin silicon oxide films from perhydropolysilazane.
► Conversion kinetics of different low temperature conversion paths were compared.
► Catalysis of low temperature conversion leads to imperfectly cured material.
► Thin films improve nitrogen and oxygen barrier properties of polymer substrates.
► Incomplete conversion of precursor is limiting water barrier properties.