Hydrogen-bonded polymer nanocomposites containing discrete layers of gold nanoparticles

Abstract

The ability to finely control the spatial location and relative concentration of a nanofiller within a polymer nanocomposite is desirable, especially when faced with fillers that are susceptible to aggregation. In the case of gold nanoparticles (AuNPs), spatial organization is of interest as it offers a means to harness optical and electrical properties, but well-defined placement of AuNPs within a polymer matrix is generally challenging because of phase separation. Here, we demonstrate for the first time the spray-assisted layer-by-layer assembly (LbL) of hydrogen-bonding polymer nanocomposites of poly(ethylene oxide) (PEO) and poly(methacrylic acid) (PMAA) containing discrete regions of AuNPs vertically positioned throughout the film structure. Analysis of the internal structure using cross-sectional transmission electron microscopy (TEM) imaging shows that the AuNP regions are clearly separated by "empty" regions of polymer with no drift or aggregation of the Au NPs during or after fabrication. A UV-vis spectroscopy study of the stimuli-responsive properties of the spray-assisted LbL nanocomposites shows the release of AuNPs as induced by elevating the environmental pH above the critical pH at which the PEO and PMAA hydrogen bonds are disrupted. We anticipate that this work enables the spatial organization of other nanofillers in stimuli-responsive hydrogen-bonding nanocomposites by spray-assisted LbL assembly.

Time–Temperature and Time–Water Superposition Principles Applied to Poly(allylamine)/Poly(acrylic acid) Complexes

“…Polyelectrolyte complexes (PECs) are the product of strong interactions between oppositely charged macromolecules and the release of entropic counterions in a solution. − PEC morphologies range from solid-like (polyelectrolyte complexes) to liquid-like (polyelectrolyte coacervates) , and are affected by assembly conditions (e.g., polyelectrolyte concentration, ionic strength and salt type, polyelectrolyte type and molecular weight, etc. ), as well as posttreatment conditions. − Consequently, PEC physical properties have proven to be affected by water content, salt, and pH. − This enables PECs for several applications including humidity sensors, , adhesives, self-healing materials, − and mechanically adaptive materials .…”

100th Anniversary of Macromolecular Science Viewpoint: Modeling and Simulation of Macromolecules with Hydrogen Bonds: Challenges, Successes, and Opportunities

“…For example, in case of poly­(ethylene oxide) (PEO) and poly­(methacrylic acid) (PMAA), the H-bonds between the acceptor (PEO) and donor (PMAA) are disrupted above the critical pH of 4.5. This pH sensitivity can be used to tune nanoparticle location and assembly within the blended matrix as done in ref . The dynamic nature of H-bonds also facilitates the design of self-healing materials ,, (e.g., Figure b) and thermally responsive porous materials in membranes …”

Thermoplasmonic dissipation in gold nanoparticle–polyvinylpyrrolidone thin films

“…32 This comparison suggests layerby-layer fabrication with control of spatial dimension and concentration could be implemented to enhance overall thermal response of PVP thin lms containing Au nanostructures. 54,55 Effects of thermal mass are more completely accounted in Fig. 2.…”