title: Shape-dependent dispersion and alignment of nonaggregating plasmonic gold nanoparticles in lyotropic and thermotropic liquid crystals.
abstract: We use both lyotropic liquid crystals composed of prolate micelles and thermotropic liquid crystals made of rod-like molecules to uniformly disperse and unidirectionally align relatively large gold nanorods and other complex-shaped nanoparticles at high concentrations. We show that some of these ensuing self-assembled orientationally ordered soft matter systems exhibit polarization-dependent plasmonic properties with strongly pronounced molar extinction exceeding that previously achieved in self-assembled composites. The long-range unidirectional alignment of gold nanorods is mediated mainly by anisotropic surface anchoring interactions at the surfaces of gold nanoparticles. Polarization-sensitive absorption, scattering, and extinction are used to characterize orientations of nanorods and other nanoparticles. The experimentally measured unique optical properties of these composites, which stem from the collective plasmonic effect of the gold nanorods with long-range order in a liquid crystal matrix, are reproduced in computer simulations. A simple phenomenological model based on anisotropic surface interaction explains the alignment of gold nanorods dispersed in liquid crystals and the physical underpinnings behind our observations.
authors.affiliation: Department of Physics and Materials Science and Engineering Program, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Qingkun
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou 310058, People's Republic of China.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Tang
authors.affiliation: Department of Physics and Materials Science and Engineering Program, University of Colorado at Boulder, Boulder, Colorado 80309, USA and Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou 310058, People's Republic of China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Physics and Materials Science and Engineering Program, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
authors.forename: Angel
authors.initials: A
authors.lastname: Martinez
authors.affiliation: Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou 310058, People's Republic of China.
authors.forename: Shaowei
authors.initials: S
authors.lastname: Wang
authors.affiliation: Centre for Optical and Electromagnetic Research, Zhejiang University, Hangzhou 310058, People's Republic of China.
authors.forename: Sailing
authors.initials: S
authors.lastname: He
authors.affiliation: Air Force Research Laboratory, Materials and Manufacturing Directorate, WPAFB, OH, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: White
authors.affiliation: Department of Physics and Materials Science and Engineering Program, University of Colorado at Boulder, Boulder, Colorado 80309, USA and Department of Electrical, Computer, and Energy Engineering and Liquid Crystals Materials Research Center, University of Colorado at Boulder, Boulder, Colorado 80309, USA and Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, Colorado 80309, USA.
authors.forename: Ivan I
authors.initials: II
authors.lastname: Smalyukh
mesh_terms: D016880:Anisotropy; D003102:Colloids; D003198:Computer Simulation; D005898:Glass; D017612:Gold Compounds; D008027:Light; D050866:Liquid Crystals; D053768:Metal Nanoparticles; D008823:Micelles; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008962:Models, Theoretical; D061848:Optical Imaging; D010706:Phosmet; D011092:Polyethylene Glycols; D013057:Spectrum Analysis; D013499:Surface Properties
chemical_list: D003102:Colloids; D017612:Gold Compounds; D008823:Micelles; D011092:Polyethylene Glycols; C028210:monomethoxypolyethylene glycol; D010706:Phosmet