(191a) Engineering of Multilayered Nanoparticles Structures for Stretchable Conductors With Self-Organized Conductive Pathways

Kim, Y., University of Michigan
Zhu, J., University of Michigan
Yeom, B., University of Michigan
Kotov, N. A., University of Michigan
Su, X., University of Michigan
Uher, C., University of Michigan

Stretchable conductors are essential components of next generation electronic devices that can facilitate integration of human-machine interfaces.  Despite the fundamental difficulties of combining stretchability and conductivity tremendous research and development efforts have been put into exploring possibilities envisioned from nanoscale building blocks with various polymeric matrixes.  Carbon nanotubes (CNTs) have been chosen mainly because of its high aspect ratio that enabled low percolation threshold and good electrical properties during mechanical deformation. Typical stretchable conductors from CNTs, however, have several problems; high quality of composite is not reproducible, metallic conductivity is unlikely, and properties are anisotropic. To overcome those problems, we present a systematic approach making stretchable conductors from extreme content of nanoparticles (NPs) with polymer matrix by layer-by-layer (LBL) assembly technique. To highlight the structural influences on the properties of composites, layered composites by vacuum-assisted flocculation (VAF) method were also prepared.  NPs, in general, might be an inadequate choice as fillers because they have minimal aspect ratio, however specially synthesized NPs with judiciously chosen polymer matrix are expected to have better electromechanical properties.  Indeed, unexpectedly high electrical and mechanical properties with metallic charge transport mechanism were observed and these were originated from dynamic self-assembly of NPs under stress.  Theoretical study about dynamic conducting percolation showed excellent match with experimental data.  Also, stretchable nanoparticle conductor composites showed a new approach of electro-tuning mechanical properties.  Scanning electron microscope, transmittance electron microscope, atomic force microscopy, electrical properties measurement system, dynamic mechanical analysis, small-angle X-ray scattering were performed to analyze properties of nanocomposites.