Water permeation through organic–inorganic multilayer thin films

We prepared organic (self-assembled monolayer (SAM))–inorganic (TiO2) multilayer barrier films on polyethylene terephthalate substrate using atomic layer deposition and molecular layer deposition methods in the same deposition chamber. The water permeation was mainly blocked by the inorganic TiO2 layer. While the lag time was proportional to the thickness of the TiO2 layer, the steady-state permeation rate was relatively independent of the thickness. The multilayer approach was effective in extending the lag time due to both the tortuous path effect and the internal desiccant effect. Water permeation occurred sequentially in the organic–inorganic multilayer barriers by water accumulation in the organic SAM layers. The water vapor transmission rate was 7.0 × 10− 4 g/m2·day during the lag time of 155 h at 60 °C and a relative humidity of 85% with 5-dyad barrier film.

► TiO2 and self-assembled monolayer (SAM) are grown by layer-by-layer deposition. ► We showed that the SAM layer is beneficial due to its internal desiccant effect. ► Water vapor transmission rate of the film is measured by electrical Ca test.