(645e) Super Gas Barrier of All-Polymer Layer-by-Layer Assemblies

Layer-by-layer assembly of cationic polyethylenimine (PEI) and anionic poly (acrylic acid) (PAA) was investigated with regard to pH of each polymer during deposition. Thickness and surface roughness can be altered dramatically due to the pH-responsive morphology of PEI and PAA.  The oxygen permeability of an 8-bilayer, glutaraldehyde-crosslinked PEI/PAA film (305 nm thick) is below 3.2×10^-21 cm³·cm/cm²·s·Pa, which is believed to be the lowest permeability of an all-polymer system ever reported. It is believed that this transparent thin film has a structure akin to a highly interpenetrating network that contributes to its impressive oxygen barrier behavior.  Even at 100% RH this film is able to maintain high gas barrier.  This relatively simple recipe may be of use for a variety of packaging applications, including flexible electronics that require high flexibility and transparency.