Genaro A. Gelves

Highly electrically conductive and high performance EMI shielding nanowire/polymer nanocomposites by miscible mixing and precipitation

Metal nanowire/polymer nanocomposites are advanced materials for electrically conductive applications. Metal nanowires have high surface area, high aspect ratios, and high electrical conductivity, which are critical for the synthesis of conductive polymer nanocomposites using extremely low amounts of conductive filler. In this work, lightweight, thin, and highly conductive copper nanowire/polystyrene nanocomposites were prepared using a novel method of nanocomposite preparation termed miscible solvent mixing and precipitation (MSMP). Suspensions of high aspect ratio copper nanowires were mixed with polystyrene solutions to produce polymer nanocomposites with segregated nanowire networks resembling cell-like structures. Highly electrically conductive networks of nanowires were obtained beyond a percolation threshold of ϕc = 0.67 vol% and percolated nanocomposites showed electrical conductivities up to 104 S m−1, which exceeds the conductivity range generally reported for carbon nanofiller-based nanocomposites. The significant potential of these nanocomposites for electrical applications like electromagnetic interference (EMI) shielding was further demonstrated. Metal nanowire/polymer nanocomposites sheets of 0.21 mm in thickness exhibited EMI SE of more than 20 dB for copper nanowire concentrations of only 1.3 vol%.

Multigram synthesis of copper nanowires using ac electrodeposition into porous aluminium oxide templates

Multigram quantities of Cu nanowires ca. 25 nm in diameter and µm in length have been produced by AC electrodeposition into porous aluminium oxide (PAO) templates. Multiple, large-area Al electrodes (5 × 11 cm or 10 × 25 cm) are anodized in parallel at 25.0 V in 0.3 M H2SO4(aq) using custom built baths. The pores are efficiently filled by applying 200 Hz sine waves at 10 Vrms between the anodized Al and Cu plate counter electrodes immersed in a 0.50 M CuSO4(aq) solution. Dissolution of the PAO template in 0.6 M H3PO4 to free the Cu nanowires results in significant coarsening of the nanowires, whereas dissolution of the PAO template in 1.0 M NaOH(aq) results in retention of the Cu nanowire diameters corresponding to the pore diameter of the PAO template. Liberated Cu nanowires were characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy.