Super Gas Barrier of All-Polymer Multilayer Thin Films

Abstract

Thin film assemblies of branched polyethylenimine (PEI) and poly(acrylic acid) (PAA), deposited using the layer-bylayer 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 μm for 30-bilayer films). Cross-linking these films with glutaraldehyde (GA) create an inhibition of polymer interdiffusion, causing exponential film growth to be reset. AFM images show the surface morphology of PEI/PAA assemblies can be controlled by the pH and the final polymer layer deposited, with surface roughness ranging from 2.1 to 49.1 nm. Most pH combinations failed to produce a film with high oxygen barrier, but 8 bilayers of PEI at pH 10 and PAA at pH 4 produce a 305 nm thick film with an oxygen transmission rate below 0.005 cm 3 /(m 2 day). This unique thin film barrier (P O 2 < 3.2 Â 10 -21 cm 3 (STP) cm/(cm 2 s Pa)) is a promising alternative to current polymeric membranes, flexible electronics, and food packaging materials.

Protein detection using tunable pores: resistive pulses and current rectification

“…In an attempt to introduce a facile method for modifying the surface chemistry of the pore a layer-bylayer LbL, assembly using PEI/PAAMA was investigated. This system is well studied having been previously used to modify a range of materials [50][51][52][53][54][55] . We favoured this technique over other PU treatments such as plasma or the incorporation of grafting polymers into the matrix via swelling 47,56,57 , as it allows for a simply and rapid dip coating strategy.…”

Active Packaging Coatings

“…Deposition can be accomplished either by submersion of the substrate into polyelectrolyte solutions or by spraying of solutions onto the substrate; both techniques have potential for scalability as high throughput coating technologies. The deposition of the polyelectrolytes can be optimized by adjusting the pH of their solutions to a point of full protonation or deprotonation, to maximize the presence of charge [30]. The deposition can rely exclusively on electrostatic interactions [29,31], or covalent bonds can be built between the alternating layers through the use of crosslinkers [25,29,32,33].…”

Surface and Bulk Modification of Synthetic Textiles to Improve Dyeability

“…The increased coating thickness improved electrical conductivity (.cf Figure 9). The coated textiles also showed considerable improvement in UV and visible light shielding as examined by UV/Vis spectrometer (Wei et al, 2008).…”

“…9. Surface morphology of textile fiber: (a) original polypropylene fiber; (b) 20nm copper coated polypropylene fiber; (c) 50nm copper coated polypropylene fiber; and (d) 100nm copper coated polypropylene fiber (Wei et al, 2008).…”