Thin films of branched polyethylenimine (PEI) and poly(acrylic acid) (PAA), prepared using layer-by-layer assembly, have been 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 (GA) resets exponential growth by inhibiting polymer interdiffusion. AFM images show the surface morphology of PEI/PAA changes according to pH, with surface roughness ranging from 2.1 to 49.1 nm.  An oxygen transmission rate below 0.005 cm3/(m2 day) is obtained with an 8 bilayer film of PEI at pH 10 and PAA at pH 4, having a thickness of only 305 nm. This unique thin film barrier (PO2 < 3.2 � 10-21 cm3 (STP) cm/(cm2 s Pa)) is a promising alternative to current polymeric membranes, flexible electronics, and food packaging materials.

Super gas barrier of all polymer multilayer films

244th National Meeting (2012)

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