Simple Preparation of Photoluminescent and Color-Tunable Polyester Resin Blended with Alkaline-Earth-Activated Aluminate Nanoparticles

Optical properties of novel luminescent nacre-like epoxy/graphene nanocomposite coating integrated with lanthanide-activated aluminate nanoparticles

Nacre structure has aragonite polygonal tablets, tessellated to generate separate layers, and exhibits adjacent layers and tablets within a layer bonded by a biopolymer. Herein, we report the development of nacre-like organic/inorganic hybrid nanocomposite coating consisting of epoxy tablets as well as rare-earth activated aluminate and graphene oxide tablet/tablet interfaces. The lanthanide-activated aluminate was prepared by the high temperature solid-state approach followed by the top-down technology to provide the phosphor nanoparticles (PNPs). Graphene oxide nanosheets were prepared from graphite. The prepared epoxy/graphene/phosphor nanocomposites were applied onto mild steel. Covalent bonds were formed between epoxy polymer chains resin and graphene oxide nanosheets. Those interface interactions results in tough surface, high tensile strength, and excellent durability. The usage of phosphor in the nanoparticle form guaranteed no agglomerations were produced throughout the hardening procedure by allowing better distribution of PNPs in the nacre-like matrix. The generated nacre-like substrates displayed reversible fluorescence. The excitation of the white colored nacre-like coats at 367 nm results in a green emission band at 518 nm as designated by CIE Lab and photoluminescence spectra. Various analysis methods were utilized to inspect the surface structure and elemental composition of the nacre-like coats. An improved hydrophobicity and mechanical characteristics were detected with increasing the phosphor concentration. Due to the astonishing characteristics of the prepared nacre-like composite paint, both ceramics and metals can benefit from the current simple strategy.

Simple preparation of novel photochromic polyvinyl alcohol/carboxymethyl cellulose security barcode incorporated with lanthanide-doped aluminate for anticounterfeiting applications

Forgery and low-quality products pose a danger to the society. Therefore, there are increasing demands for the production of easy to recognize and difficult to copy anti-counterfeiting materials. Products with smart photochromic and fluorescent properties can change color and emission spectra responding to a light source. In this context, we devised a straightforward preparation of luminescent polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC) nanocomposite to function as a transparent labeling film. The lanthanide-doped aluminate (LdA) was prepared in the nanoparticle form to indicate diameters of 35-115 nm. Different ratios of the lanthanide-doped aluminate (LdA) were physically dispersed in the PVA/CMC nanocomposite label film to provide photochromic, ultraviolet protection, antimicrobial activity and hydrophobic properties. Fluorescence peaks were detected at 365 and 519 nm to indicate a color change to green. As a result of increasing the phosphor ratio, improved superhydrophobic activity was achieved as the contact angle increased from 126.1° to 146.0° without affecting the film original physical and mechanical properties. Both UV protection and antibacterial activity were also investigated. The films showed quick and reversible photochromic response without fatigue. The current strategy reported the development of photochromic smart label that is transparent, cost-effective and flexible. As a result, numerous anticounterfeiting products can benefit from the current label for a better market. LdA-loaded PVA/CMC films demonstrated antibacterial activity between poor, good, very good and outstanding as the percentage of LdA in the film matrix increased. The current film can be applied as a transparent photochromic security barcode for anticounterfeiting applications and smart packaging.