In a new research project conducted by scientists at Ferdowsi University of Mashhad and the Department of Chemistry at the University of Zanjan, multifunctional latex nanoparticles with both colorimetric and fluorescent properties have been developed.
According to the Report, These nanoparticles are capable of responding to environmental changes and were synthesized through a one-step emulsion polymerization method. They show wide-ranging applications in areas such as latent fingerprint (LFP) detection, anti-counterfeiting inks, and organic light-emitting diodes (OLEDs). The study also advances the development of materials with diverse optical properties that can play a key role in smart technologies and various industries.
With the rapid progress of nanotechnology, the demand for smart materials responsive to environmental stimuli is growing. Such materials not only have applications in electronics, security, and medicine but also significantly enhance detection and identification capabilities. One of the notable features of these materials is their ability to change color and fluorescence in response to specific environmental conditions. The latex nanoparticles developed in this study exhibit environment-sensitive color shifts and light emission depending on solvent polarity and polymeric environments.
In this research, multifunctional latex nanoparticles containing different functional groups such as amide, amine, acid, hydroxyl, epoxy, and long-chain esters were synthesized via one-step emulsion polymerization. These nanoparticles range from 45 to 170 nanometers in size and take spherical or anisotropic (non-spherical) forms depending on the polarity of their functional groups. After synthesis, the latex nanoparticles were modified with an oxazolidine derivative (5 wt%) to impart distinct colorimetric and fluorescent properties.
The study investigated the effect of environmental conditions and functional group polarity on the colorimetric behavior of oxazolidine. Results showed that in the solution phase, solvent polarity was the key factor influencing color changes, whereas in the solid phase, the interactions between oxazolidine molecules and the polymer functional groups largely determined the optical responses.
The colored and fluorescent polymeric nanoparticles obtained in this work are suitable for producing anti-counterfeiting inks, optical security labels, and latent fingerprint detection under both visible and UV light. Another promising application is their use in OLED fabrication, where emission characteristics can be tuned based on functional group polarity.
These fluorescent nanoparticles, in particular, have great potential in latent fingerprint detection through powder dusting and fluorescent imaging techniques. In this study, they were successfully applied to reveal fingerprints under visible and UV illumination. Moreover, the nanoparticles can serve as anti-counterfeiting inks for printing security labels on cellulosic papers.
This research not only introduces a new class of polymeric materials with diverse optical properties but also opens new horizons for their application in sensors, smart inks, and organic electronics. The findings highlight that latex nanoparticles with environmental sensitivity can serve as highly functional materials in advanced technologies such as security printing, optoelectronics, and fingerprint recognition systems.
The results have been published in Chemical Engineering Journal under the title:
“Colorimetric and fluorimetric microenvironment responsivity of oxazolidine in solvatochromic latex nanoparticles: Versatile intelligent polymeric materials with advanced applications.”