title: Reconfigurable chiroptical nanocomposites with chirality transfer from the macro- to the nanoscale.
abstract: Nanostructures with chiral geometries exhibit strong polarization rotation. However, achieving reversible modulation of chirality and polarization rotation in device-friendly solid-state films is difficult for rigid materials. Here, we describe nanocomposites, made by conformally coating twisted elastic substrates with films assembled layer-by-layer from plasmonic nanocolloids, whose nanoscale geometry and rotatory optical activity can be reversibly reconfigured and cyclically modulated by macroscale stretching, with up to tenfold concomitant increases in ellipticity. We show that the chiroptical activity at 660 nm of gold nanoparticle composites is associated with circular extinction from linear effects. The polarization rotation at 550 nm originates from the chirality of nanoparticle chains with an S-like shape that exhibit a non-planar buckled geometry, with the handedness of the substrate's macroscale twist determining the handedness of the S-like chains. Chiroptical effects at the nexus of mechanics, excitonics and plasmonics open new operational principles for optical and optoelectronic devices from nanoparticles, carbon nanotubes and other nanoscale components.
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, USA.|Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109-2136, USA.
authors.forename: Yoonseob
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, USA.|Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109-2136, USA.|Department of Chemical Engineering, Myongji University, Yongin, Gyeonggi-do 449-728, South Korea.
authors.forename: Bongjun
authors.initials: B
authors.lastname: Yeom
authors.affiliation: Departamento Física Aplicada i Òptica, Universitat de Barcelona, Barcelona 08028, Spain.
authors.forename: Oriol
authors.initials: O
authors.lastname: Arteaga
authors.affiliation: Nano-Bio Electron Microscopy Research Group, Korea Basic Science Institute (KBSI), 169-148 Gwahak-ro, Yuseong-gu, Daejeon 34133, Republic of Korea.
authors.forename: Seung
authors.initials: S
authors.lastname: Jo Yoo
authors.affiliation: Nano-Bio Electron Microscopy Research Group, Korea Basic Science Institute (KBSI), 169-148 Gwahak-ro, Yuseong-gu, Daejeon 34133, Republic of Korea.
authors.forename: Sang-Gil
authors.initials: SG
authors.lastname: Lee
authors.affiliation: Nano-Bio Electron Microscopy Research Group, Korea Basic Science Institute (KBSI), 169-148 Gwahak-ro, Yuseong-gu, Daejeon 34133, Republic of Korea.
authors.forename: Jin-Gyu
authors.initials: JG
authors.lastname: Kim
authors.affiliation: Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, USA.|Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109-2136, USA.
authors.forename: Nicholas A
authors.identifier: http://orcid.org/0000-0002-6864-5804
authors.initials: NA
authors.lastname: Kotov
mesh_terms: D003102:Colloids / Q000737:chemistry; D008567:Membranes, Artificial; D053761:Nanocomposites / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010316:Particle Size
chemical_list: D003102:Colloids; D008567:Membranes, Artificial; D037742:Nanotubes, Carbon