Thin film assemblies of branched polyethylenimine (PEI) and poly(acrylic acid) (PAA), deposited using the layer-by-layer technique, were studied in an effort to produce all-polymer thin films with low oxygen permeability. Altering the pH of PEI and PAA results in large thickness variations (from 90 nm to 4.74 �m for 30-bilayer films). Cross-linking these films with glutaraldehyde inhibits polymer interdiffusion consequently resetting exponential film growth. AFM images show the surface morphology of PEI/PAA assemblies can be controlled by the pH and the final polymer layer deposited. Oxygen permeability of a cross-linked 8 bilayer film of PEI at pH 10 and PAA at pH 4 is less than 3.2 � 10-21 cm3 (STP) cm/(cm2 s Pa) at a thickness of just 305 nm. This unique thin film barrier is a promising alternative to current polymeric membranes, flexible electronics, and food packaging materials.

Super gas barrier of all-polymer multilayer thin films

245th National Meeting (2013)

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