Photochromic materials have attracted broad interest to enhance the anti-counterfeiting of commercial products. In order to develop anti-counterfeiting mechanically reliable composite materials, it is urgent to improve the engineering process of both the material and matrix. Herein, we report on the development of anti-counterfeiting mechanically reliable nanocomposites composed of rare-earth doped aluminate strontium oxide phosphor (RESA) nanoparticles (NPs) immobilized into the thermoplastic polyurethane-based nanofibrous film successfully fabricated via the simple solution blowing spinning technology. The generated photochromic film exhibits an ultraviolet-stimulated anti-counterfeiting property. Different films of different emissive properties were generated using different total contents of RESA. Transmission electron microscopy was utilized to investigate the morphological properties of RESA NPs to display a particle diameter of 3-17 nm. The morphologies, compositions, optical transmittance, and mechanical performance of the produced photochromic nanofibrous films were investigated. Several analytical methods were employed, including energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier-transform infrared spectrometry. The fibrous diameter of RESA-TPU was in the range of 200-250 nm. In order to ensure the development of transparent RESA-TPU film, RESA must be prepared in the nanosized form to allow better dispersion without agglomeration in the TPU matrix. The luminescent RESA-TPU film displayed an absorbance intensity at 367 nm and two emission intensities at 431 and 517 nm. The generated RESA-TPU films showed an enhanced hydrophobicity without negatively influencing their original appearance and mechanical properties. Upon irradiation with ultraviolet light, the transparent nanofibrous films displayed rapid and reversible photochromism to greenish-yellow without fatigue. The produced anti-counterfeiting films demonstrated stretchable, flexible, and translucent properties. As a simple sort of anti-counterfeiting substrates, the current novel photochromic film provides excellent anti-counterfeiting strength at low-cost as an efficient method to develop versatile materials with high mechanical strength to create an excellent market as well as adding economic and social values.

Development of Mechanically Reliable and Transparent Photochromic Film Using Solution Blowing Spinning Technology for Anti-Counterfeiting Applications.

Synthesis and competitive luminescence quenching mechanism of Ca3Al2O6:Ln3+ (Ln: Dy and Sm) phosphors

Structural and optical characterization of trivalent samarium-activated LaAlO3 nanocrystalline materials for solid-state lighting

Smart textiles with a multifunctional surface, such as with photoluminescence, antimicrobial, and superhydrophobic properties, are highly desirable. Silver nanoparticles (Ag NPs) were prepared and immobilized onto a cotton surface using a facile pad-dry-curing technique to introduce long-lasting antimicrobial properties. The morphology of the silver immobilized cotton fibres was explored using scanning electron microscopic images and energy-dispersive X-ray spectra. The morphology of the formed Ag NPs was determined using a transmission electron microscope. Ag NPs exhibited uniform spreading and a high deposition density with a particle diameter in the range 25-55 nm. Both photoluminescence and superhydrophobic properties were explored by studying the cotton samples treated with hexadecyltrimethoxysilane nanocomposite containing lanthanide-doped strontium oxide aluminate NPs. Ultraviolet-visible light absorption, phosphorescence, and lifetime spectra were measured. The produced transparent superhydrophobic and photoluminescent film showed two absorbance bands at 273 and 367 nm and emission bands at 415 and 437 nm, as recognized by both absorption and emission spectra. Excellent antibacterial activities towards E. coli and S. aureus were monitored for the coated samples. Both fastness and colorimetric properties of Ag NPs-coated fabrics were explored.

Immobilization of silver and strontium oxide aluminate nanoparticles integrated into plasma-activated cotton fabric: luminescence, superhydrophobicity, and antimicrobial activity

Structural, thermal and light emission properties of Eu, Sm, Dy, Er and Mn doped CaAl2O4 and SrAl2O4

Semi-organic nonlinear optical (NLO) 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals have been grown by slow evaporation solution technique (SEST) with the growth period of 60 days. The single-crystal XRD analysis confirms the unit cell parameters of the grown crystal. The crystallinity of grown 2A5NPBr was analyzed by powder X-ray diffraction (PXRD) measurement. The presence of functional groups of 2A5NPBr crystal was confirmed by Fourier transform infrared (FTIR) spectrum analysis. The optical transmittance of the grown crystal was analyzed by UV–Vis–NIR analysis. It shows good transparency in the visible and NIR region and it is favorable for nonlinear optical (NLO) device applications. The chemical etching study was carried out and it reveals that the grown crystal has less dislocation density. The photoconductivity study reveals that the grown crystal possesses positive photoconductive nature. The thermal stability of the crystal has been investigated by thermogravimetric (TG) and differential thermal analysis (DTA). The dielectric constant and dielectric loss as a function of frequency were measured. The electronic polarizability (α) of 2A5NPBr molecule has been calculated theoretically by different ways such as Penn analysis, Clausius–Mossotti relation, Lorentz–Lorenz equation, optical bandgap, and coupled dipole method (CDM). The obtained values of electronic polarizability (α) are in good agreement with each other. Laser damage threshold (LDT) of 2A5NPBr crystal has been measured using Nd:YAG laser with the wavelength of 1064 nm. Third-order nonlinear optical property of the grown crystal was studied by Z-scan technique using He–Ne laser of wavelength 632.8 nm.

Crystal growth and characterization of semi-organic 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals for third-order nonlinear optical (NLO) applications

Dysprosium activated strontium aluminate phosphor: A potential candidate for WLED applications

We report the growth process and linear and nonlinear optical characterization of high quality improvised semiorganic 2A5NPDP single crystal using the modified SR method for the first time. The maj...

Evaluation of Linear and Nonlinear Optical Properties of D−π–A Type 2-Amino-5-Nitropyridinium Dihydrogen Phosphate (2A5NPDP) Single Crystal Grown by the Modified Sankaranarayanan–Ramasamy (SR) Method for Terahertz Generation

Tunable photoluminescence properties of Dy3+ doped LLZO phosphors for WLED and dosimetry applications

https://link.springer.com/content/pdf/10.1007/s11696-021-01915-1.pdf

Raja Arumugam

Papers

Crystal growth and characterization of semi-organic 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals for third-order nonlinear optical (NLO) applications

Dysprosium activated strontium aluminate phosphor: A potential candidate for WLED applications

Evaluation of Linear and Nonlinear Optical Properties of D−π–A Type 2-Amino-5-Nitropyridinium Dihydrogen Phosphate (2A5NPDP) Single Crystal Grown by the Modified Sankaranarayanan–Ramasamy (SR) Method for Terahertz Generation

Tunable photoluminescence properties of Dy3+ doped LLZO phosphors for WLED and dosimetry applications

Reddish-orange-emitting Ca12Al14O33: Sm3+ phosphors with high color purity