Expanding the Horizon of Mechanochromic Detection by Luminescent Shear Stress Sensor Supraparticles

Wintzheimer, Susanne; Reichstein, Jakob; Wenderoth, Sarah; Hasselmann, Sebastian; Oppmann, Maximilian; Seuffert, Marcel T.; Müller‐Buschbaum, Klaus; Mandel, Karl

doi:10.1002/adfm.201901193

Cited by 30 publications

(34 citation statements)

References 68 publications

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“…1,2,3,4,5,6,7 Intense researches are currently devoted to luminescent mechanochromic materials exhibiting reversible emission color changes activated by mechanical stimulation, because of their promising sensor applications. 8,9,10,11,12,13,14,15,16,17,18,19,20 In the last decade, the number of reports on luminescent mechanochromic compounds keeps increasing 21,22 with a majority of organic compounds 23,24 compared with the metal-based ones which are mainly based on gold 25 and platinum 26 complexes. Despite this plethora of studies, thorough investigations to understand the mechanisms at play still remain relatively scarce.…”

Section: Introductionmentioning

confidence: 99%

Combining Theory and Experiment to Get Insight into the Amorphous Phase of Luminescent Mechanochromic Copper Iodide Clusters

et al. 2020

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In the field of stimuli-responsive luminescent materials, mechanochromic compounds exhibiting reversible emission color changes activated by mechanical stimulation, present appealing perspectives in sensor applications. The mechanochromic luminescence properties of the molecular cubane copper iodide cluster [Cu4I4(PPh2(C6H4-CH2OH))4] (1), are reported in this study. This compound can form upon melting an amorphous phase giving an unprecedented opportunity to investigate the mechanochromism phenomenon. Because the mechanically induced crystalline-toamorphous transition is only partial, the completely amorphous phase represents the ultimate state of the mechanically altered phase. Furthermore, the studied compound could form two different crystalline polymorphs namely 1•CH3CN and 1•THF, allowing establishment of straightforward structureproperties relationships. Photophysical and structural characterizations of 1 in different states were performed and the experimental data were supported by theoretical investigations. Solid-state NMR (Nuclear Magnetic Resonance) analysis permit to quantify the amorphous part in the mechanically altered phase. IR (Infra-Red) and Raman analysis enabled identification of the spectroscopic signatures of each states. DFT (density functional theory) calculations led to assignment of both the NMR characteristics and the vibrational bands. Rationalization of the photoluminescence properties was also conducted with simulation of the phosphorescence spectra allowing an accurate interpretation of the thermochromic luminescence properties of this family of compounds. The combined study of crystalline polymorphism and amorphous state permit to get deeper into the mechanochromism mechanism that implies changes of the [Cu4I4] cluster core geometry. By combining multi-stimuli responsive properties, copper iodide clusters constitute an appealing class of compounds towards original functional materials.

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Section: Introductionmentioning

confidence: 99%

Combining Theory and Experiment to Get Insight into the Amorphous Phase of Luminescent Mechanochromic Copper Iodide Clusters

et al. 2020

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“…In principle, these building blocks might seem very similar to the ones described by us in a previous publication. [ 16 ] However, the resulting indicator system of this preliminary work was based on a rather complex multi‐particle‐object‐system, whereas herein, a single‐entity‐system is established, i.e., all three indicator components are hierarchically collocated within one single supraparticle entity. In addition to this clear difference, the newly developed indicator supraparticles come with further significant advantages.…”

Section: Resultsmentioning

confidence: 99%

Abrasion Indicators for Smart Surfaces Based on a Luminescence Turn‐On Effect in Supraparticles

Wenderoth¹,

Granath

Prieschl

et al. 2020

Advanced Photonics Research

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Many surfaces of man-made objects are equipped with a coating. The coating fulfills specific functions, for instance, as easy-to-clean, [1] scratch-resistant, [2] antireflexive, [3] or antimicrobial [4] agent. These functional properties are usually achieved via molecular building blocks, by nanoparticulate coating additives or by imprinting a surface texture. A certain degree of "smartness" can also be achieved by combining several additives [5,6] which may turn a surface into a gas sensor, [7] a corrosion protection layer, [8] or a self-healing layer. [9] Although there have always been solutions to identify deformations in components, such as in metals [10] or polymer parts, [11] the detection of damages within a surface coating which is only a few micrometers thick still remains a challenge. [12] Such a "scratch-detecting" surface indicator must be cheap, easy to manufacture, easy to detect and should be applicable to any type of surface. Some additives for bulk materials have already been presented which are able to detect scratches and repair them directly. [13] A disadvantage of these systems is, however, that they only do work in a bulk material and not in a coating of a few microns thickness. In this study, we report on shear stress indicators in the form of so-called supraparticles that can be used as damage detectors in thin coatings. These indicator supraparticles are micron-sized, hierarchically structured particles and are composed of nanoparticles. The great advantage of such supraparticles is that a number of very different properties can be combined by assembling different nanoparticle building blocks which carry specific attributes (e.g., magnetism, fluorescence, catalytic activity, etc.). [14] Forced assembly of nanoparticles can be achieved by spray-drying. This process is well-known and well established, for instance, in the pharmaceutical or food industry, to obtain dry powder products (such as granular drugs or instant coffee). [15] Complex architectures can be achieved by repeating this process: In a first spray-drying cycle, supraparticles can be formed from a nanoparticle dispersion. Within a second spray-drying cycle, the supraparticles resulting from the first spray-drying cycle can be coated with other nanoparticles to ultimately obtain core-shell supraparticles.

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“…Even after activation, residues from the StFls that are not completely decomposed could disturb the ID emission signal and thus inhibit its detection. [ 36,37 ]…”

Section: Methodsmentioning

confidence: 99%

A Supraparticle‐Based Five‐Level‐Identification Tag That Switches Information Upon Readout

Miller

Wintzheimer

Prieschl

et al. 2020

Advanced Optical Materials

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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 CaF2 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.

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Expanding the Horizon of Mechanochromic Detection by Luminescent Shear Stress Sensor Supraparticles

Cited by 30 publications

References 68 publications

Combining Theory and Experiment to Get Insight into the Amorphous Phase of Luminescent Mechanochromic Copper Iodide Clusters

Combining Theory and Experiment to Get Insight into the Amorphous Phase of Luminescent Mechanochromic Copper Iodide Clusters

Abrasion Indicators for Smart Surfaces Based on a Luminescence Turn‐On Effect in Supraparticles

A Supraparticle‐Based Five‐Level‐Identification Tag That Switches Information Upon Readout

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