(574e) Atmospheric-Pressure Plasma Patterning and Reduction of Metal-Ion Containing Polymer Films to Fabricate Stretchable Electrically Conducting Features

Additive manufacturing enables the fabrication of 2D and 3D materials for prototyping and low-cost, disposable applications by printing nanoparticle inks at the point-of-need. A major challenge is the nanoparticle inks which contain organic stabilizers that must be removed after printing by high temperature sintering and their adhesion to the substrates.

Here, we introduce a room-temperature, in situ process for the fabrication of electrically-conductive, stretchable nanocomposites. Mixtures of polyacrylic-acid (PAA) and silver ions (Ag⁺) are first cast as a thin film and subsequently exposed to an atmospheric-pressure microplasma jet. The interaction of the plasma with the film leads to reduction of the Ag⁺ and formation of Ag nanoparticles. To characterize the Ag nanoparticles, we performed X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). In addition to confirming Ag nanoparticles, we find that the Ag is only reduced at the film surface. We hypothesize that this occurs not because of limited penetration depth of the plasma process, but as a result of a unique electromigration effect whereby Ag⁺ inside the film bulk diffuses to the surface of the film during plasma exposure. The electrically conductivity of the films was assessed by two-point probe measurements. By fabricating films on an elastomeric material, PDMS, we demonstrate that electrical conductivity can be completely preserved up to 30% uniaxial strain onto the films.[1] We attribute this character to strain delocalization due to the improved adhesion between the metal and the polymer layer.

[1] S. Ghosh et al. ACS Macro Lett. 6, 194 (2017)