(255bb) Responsive Hydrogen-Bonded Polymer Nanocomposites Containing Discrete Layers of Gold Nanoparticles Prepared By Spray-Assisted Layer-By-Layer Assembly

The incorporation of nanoscale filler materials into layer-by-layer (LbL) assemblies can have dramatic effects on the properties of the resulting nanocomposites. The ability to control the location and relative concentration of the nanofiller within the LbL assembly throughout the fabrication process is desirable for producing products with specific, predictable, and reproducible properties. Here, we demonstrate for the first time the use of spray-assisted LbL assembly to produce hydrogen-bonded polymer nanocomposites of poly(ethylene oxide) (PEO) and poly(methacrylic acid) (PMAA) containing discrete regions of gold nanoparticles (AuNPs) vertically positioned throughout the film structure. Analysis of the internal structure using cross-sectional transmission electron microscopy (TEM) shows that the AuNP regions are clearly separated by "empty" regions of polymer with no drift or aggregation during or after fabrication. UV-Vis spectroscopy was utilized to confirm these observations. A brief study of the stimuli-responsive properties of the spray-assisted LbL assembled nanocomposites showed that the release of the AuNPs could be induced and modulated by elevating the environmental pH above the critical pH of the polymer system. UV-Vis spectroscopy was used to confirm/monitor the payload release. We propose that spray-assisted LbL assembly is a promising method for producing nanocomposites with tunable properties applicable to a wide range of specialty applications where strict properties requirements must be met.