Luminescence feature of new 3,6-di(thiazolidin-5-one-2-yl)-carbazole derivative: synthesis, photophysical properties, density functional theory studies, and crystal shape effect

Preparation of afterglow and photochromic fibrous mats from polypropylene plastics to detect ultraviolet light

Polypropylene textiles have been used in the development of various industrial products, such as automotives, plastic furniture, and medical tools. However, polypropylene resists dyeing due to a deficiency of active staining spots. Here, we developed a new strategy towards new afterglow and photochromic fibres from recycled polypropylene plastics using plasma-supported coloration with rare-earth activated aluminate nanoparticles (REANPs). Plasma curing was used to generate active dyeing sites on the polypropylene surface. A thin film of REANPs (2-10 nm) was deposited onto the plasma-pretreated polypropylene surface. Various analytical techniques were applied to inspect the morphology of the REANP-finished polypropylene fibres. The polypropylene dyeing activity was much improved after being exposed to plasma. Both photoluminescence analysis and Commission internationale de l'éclairage (CIE) laboratory coordinates proved that the polypropylene fibres exhibited a white colour in daylight and green in ultraviolet light. The thin afterglow layer immobilized onto the polypropylene surface exhibited an emission band of 524 nm upon excitation at 365 nm. The sliding angles dropped from 12° to 9°, but the contacting angles increased from 139.4° to 145.0° when the REANP ratio was raised. These findings show that REANP-finished polypropylene had good colourfastness, antimicrobial activity, and ultraviolet light blocking. Both stiffness and permeability to air of REANP-finished polypropylene were explored to designate excellent comfort characteristics.

Photoluminescent and photochromic smart window from recycled polyester reinforced with cellulose nanocrystals

Smart windows with long-persistent phosphorescence, UV protection, high transparency, and high rigidity were developed by easily immobilizing varying ratios of lanthanide-activated aluminate phosphor nanoscale particles within a composite of recycled polyester/cellulose nanocrystals (RPET/CNC). Cellulose nanocrystals were prepared from rice straw waste. Cellulose nanocrystals were used at low concentration as both crosslinker and drier to improve both transparency and hardness. The phosphor nanoscale particles must be distributed into the recycled polyester/cellulose nanocrystals composite bulk without agglomeration in order to produce transparent RPET/CNC substrates. Photoluminescence characteristics were also studied by using spectroscopic profiles of excitation/emission and decay/lifetime. The hardness efficiency was also examined. This transparent recycled polyester waste/cellulose nanocrystals nanocomposite smart window has been shown to change color under UV light to strong green and to greenish-yellow when it is dark, as proved by CIE Lab color parameters. It was found that the afterglow RPET/CNC smart window had phosphorescence intensities of 428, 493 and 523 nm upon excitation at 368 nm. There were evidences of improved UV shielding, photostability, and hydrophobic activity. In the presence of low phosphor ratio, the luminescent RPET/CNC substrates showed quick and reversible fluorescent photochromic activity when exposed to UV radiation.