TY  - JOUR
A1  - Miller, Franziska
A1  - Wintzheimer, Susanne
A1  - Prieschl, Johannes
A1  - Strauss, Volker
A1  - Mandel, Karl
T1  - A Supraparticle‐Based Five‐Level‐Identification Tag That Switches Information Upon Readout
JF  - Advanced Optical Materials
N2  - Product identification tags are of great importance in a globalized world with increasingly complex trading routes and networks. Beyond currently used coding strategies, such as QR codes, higher data density, flexible application as well as miniaturization and readout indication are longed for in the next generation of security tags. In this work, micron‐sized supraparticles (SPs) with encoded information (ID) are produced that not only exhibit multiple initially covert identification levels but are also irreversibly marked as “read” upon readout. To achieve this, lanthanide doped CaF\(_{2}\) nanoparticles are assembled in various quantity‐weighted ratios via spray‐drying in presence of a broad‐spectrum stealth fluorophore (StFl), yielding covert spectrally encoded ID‐SPs. Using these as pigments, QR codes, initially dominated by the green fluorescence of the StFl, could be generated. Upon thermal energy input, these particle‐based tags irreversibly switch to an activated state revealing not only multiple luminescent colors but also spectral IDs. This strategy provides the next generation of material‐based security tags with a high data density and security level that switch information upon readout and can be, therefore, used as seal of quality.
KW  - multilevel luminescence identification
KW  - rare earth doped nanoparticles
KW  - security tags
KW  - stealth fluorophores
KW  - supraparticles
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224469
VL  - 9
IS  - 4
ER  - 
TY  - JOUR
A1  - Flegler, Andreas
A1  - Schneider, Michael
A1  - Prieschl, Johannes
A1  - Stevens, Ralph
A1  - Vinnay, Thomas
A1  - Mandel, Karl
T1  - Continuous flow synthesis and cleaning of nano layered double hydroxides and the potential of the route to adjust round or platelet nanoparticle morphology
JF  - RSC Advances
N2  - Here, we report a continuous flow synthesis of nano LDH, comprising a continuous precipitation process using static mixers and followed by an immediate cleaning process via a semi-continuous centrifuge to obtain the final product in one-go. Via this synthesis setup, it is possible to independently vary the concentrations of the reactants during precipitation and at the same time ensure constant reaction conditions and an immediate "quenching" of the precipitate due to "on the flow"-washing. We found that this paves the way to adjust the synthesis parameters in a way that the final morphology of the nano-LDH particles can be controlled to be either round or platelet-like.
KW  - MgAl LDH
KW  - nano LDH
KW  - static mixer
KW  - synthesis process
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-191305
VL  - 6
IS  - 62
ER  -