Deposition Time Effect On Nanosilicate Layer-by-Layer Film Growth and Gas Barrier

Deposition Time Effect on Nanosilicate Layer-by-Layer Film Growth and Gas Barrier

     The influence of deposition time on layer-by-layer (LbL) film growth of montmorillonite (MMT) or laponite (LAP) nanosilicate paired with branched polyethylenimine (BPEI) was studied. Deposition times, from 5 seconds to 300 seconds in each ingredient, were evaluated with respect to thickness, mass deposited and film structure. The BPEI/LAP system is more dip-time dependent than the BPEI/MMT system because LAP platelets have a much smaller aspect ratio than MMT (40 vs. 200~1000). XRD suggests the gallery spacing between clay layers is insensitive to dip time, which is a key structural parameter linked to both mechanical and transport properties of these types of films. Oxygen transmission rates (OTR) are below the detection limit of commercial instrumentation (<0.005 cc/m² · day)) in both 10 sec/300 sec and 300 sec/300 sec BPEI/MMT assemblies. This study suggests LbL assemblies could be produced very quickly, which should make this thin film coating technology more commercially appealing.