Fast spray deposition of super gas barrier polyelectrolyte multilayer thin films

Spray-assisted deposition of layer-by-layer (LbL) assemblies was originally developed to reduce the processing time of multilayer thin films. Despite being faster, spraying largely failed to convert dipping practitioners due to lack of consensus regarding the quality of spray-coated films. In an effort to allay this concern, the barrier property of spray and dip-coated polyethylenimine [PEI]/poly(acrylic acid) [PAA] bilayers (BL) was compared. A 7 BL film deposited using optimized spraying parameters was found to be thicker than a dip-coated film prepared with the same deposition time. This larger thickness generated through suppressed polyelectrolyte desorption can effectively enhance the diffusion path of gas molecules, leading to a better gas barrier. This study marks the first report showing that a multilayer assembly with better properties can be produced with spray-assisted deposition. The ability to quickly deposit higher performance thin films using spraying opens up tremendous opportunity for continuous production on a commercial scale.