Filters

2015 - 201922020 - 20211

More filters

2019 - 201922020 - 20211
Reset filters

Settings

Subject: photonic crystals × WGL Institute: INM ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Flexible distributed Bragg reflectors from nanocolumnar templates
    (Hoboken, NJ : Wiley, 2015) Calvo, Mauricio E.; González-García, Lola; Parra-Barranco, Julián; Barranco, Angel; Jiménez-Solano, Alberto; González-Elipe, Agustín R.; Míguez, Hernán
    A flexible distributed Bragg reflector is made by the infiltration of a nanocolumnar array with polydimethyl siloxane oligomers. The high optical reflectance displayed by the final material is a direct consequence of the high refractive index contrast of the columnar layers whereas the structural stability is due to the polymer properties.
  • Thumbnail Image
    Item
    Dye-Loaded Mechanochromic and pH-Responsive Elastomeric Opal Films
    (Weinheim : Wiley-VCH, 2021) Winter, Tamara; Boehm, Anna; Presser, Volker; Gallei, Markus
    In this work, the preparation and fabrication of elastomeric opal films revealing reversible mechanochromic and pH-responsive features are reported. The core–interlayer–shell (CIS) particles are synthesized via stepwise emulsion polymerization leading to hard core (polystyrene), crosslinked interlayer (poly(methyl methacrylate-co-allyl methacrylate), and soft poly(ethyl acrylate-co-butyl acrylate-co-(2-hydroxyethyl) methacrylate) shell particles featuring a size of 294.9 ± 14.8 nm. This particle architecture enables the application of the melt-shear organization technique leading to elastomeric opal films with orange, respectively, green brilliant reflection colors dependent on the angle of view. Moreover, the hydroxyl moieties as part of the particle shell are advantageously used for subsequent thermally induced crosslinking reactions enabling the preparation of reversibly tunable mechanochromic structural colors based on Bragg's law of diffraction. Additionally, the CIS particles can be loaded upon extrusion or chemically by a postfunctionalization strategy with organic dyes implying pH-responsive features. This convenient protocol for preparing multi-responsive, reversibly stretch-tunable opal films is expected to enable a new material family for anti-counterfeiting applications based on external triggers.
  • Thumbnail Image
    Item
    Nanoporous Anodic Alumina Photonic Crystals for Optical Chemo- and Biosensing: Fundamentals, Advances, and Perspectives
    (Basel : MDPI, 2018) Law, Cheryl Suwen; Lim, Siew Yee; Abell, Andrew D.; Voelcker, Nicolas H.; Santos, Abel
    Optical sensors are a class of devices that enable the identification and/or quantification of analyte molecules across multiple fields and disciplines such as environmental protection, medical diagnosis, security, food technology, biotechnology, and animal welfare. Nanoporous photonic crystal (PC) structures provide excellent platforms to develop such systems for a plethora of applications since these engineered materials enable precise and versatile control of light–matter interactions at the nanoscale. Nanoporous PCs provide both high sensitivity to monitor in real-time molecular binding events and a nanoporous matrix for selective immobilization of molecules of interest over increased surface areas. Nanoporous anodic alumina (NAA), a nanomaterial long envisaged as a PC, is an outstanding platform material to develop optical sensing systems in combination with multiple photonic technologies. Nanoporous anodic alumina photonic crystals (NAA-PCs) provide a versatile nanoporous structure that can be engineered in a multidimensional fashion to create unique PC sensing platforms such as Fabry–Pérot interferometers, distributed Bragg reflectors, gradient-index filters, optical microcavities, and others. The effective medium of NAA-PCs undergoes changes upon interactions with analyte molecules. These changes modify the NAA-PCs’ spectral fingerprints, which can be readily quantified to develop different sensing systems. This review introduces the fundamental development of NAA-PCs, compiling the most significant advances in the use of these optical materials for chemo- and biosensing applications, with a final prospective outlook about this exciting and dynamic field.