Synthesis of Persistent Luminescent Nanoparticles for Rewritable Displays and Illumination Applications

A protocol is presented for the synthesis of persistent luminescent nanomaterials (PLNPs) and their potential applications in rewritable displays and artistic processing utilizing the afterglow effect under ultraviolet light (365 nm) irradiation.

Our research focuses on developing functional nanomaterials. Based on precise biotechnology, we aim to achieve bioimaging, disease treatment, and physiological function regulation in a minimally invasive and highly selective fashion by using nanocomposites with luminescence, thermal, magnetic, and acoustic properties. We have demonstrated that utilizing a rigid backbone chain polymer, polymethyl methacrylate as the matrix, purely polycyclic aromatic hydrocarbons can exhibit stable and exceptionally long phosphorescent lifetimes, showcasing purely organic, room temperature phosphorescent properties.

We expect that this protocol not only provide a detailed experimental procedure for the hydrothermal synthesis of long-lasting imaging nanomaterials, but also introduce a method for the co-polymerization of persistent luminescent nanoparticles and MMA to further achieve ultraviolet mediated rewrite and luminescent applications. The hydrothermal synthesis masses of persistent luminescent nanoparticles could restrict the application of certain temperature sensitive substance, since they require relatively high reaction temperatures. Consequently, the selection of appropriate synthesis methods should be contingent on specific application and requirement.

The main research directions in our laboratory include the development of temperature sensitive luminescence, nano probe for microscopic temperature monitoring, immune cells, selective nano composite for immune imaging and therapy, and the establishment of new acoustic and magnetic responsive materials. To begin, take five milliliters of deionized water and add 10 millimolars of sodium hydroxide to it. Then add two millimolars of germanium oxide to the sodium hydroxide solution to prepare sodium germinate solution and stir the mixture at room temperature for about 30 minutes.

Next, add four millimolars of zinc chloride, 0.01 millimolars of manganese nitrate, and 600 microliters of nitric acid to 22 milliliters of deionized water, and stir until completely dissolved. Now, slowly add the sodium germinate solution to the prepared solution, and add one milliliter of polyethylene glycol. Then place the calibrated pH meter probe into the solution to monitor the pH value.

Add ammonium hydroxide with a mass fraction of 25 to 28%to the solution, drop by drop, and adjust the pH to 6.0, 8.0, or 9.4. Cover the beaker with ceiling film and stir the solution at room temperature for one hour while maintaining a constant stirring speed. Afterward, transfer the solution to a Teflon line to autoclave and place it in an electric, thermostatic drying oven at 220 degrees Celsius for four hours.

After completion, turn off the oven and let the system cool to room temperature. Before taking out the reactor, open the reactor slowly and transfer the reaction solution to 250 milliliter centrifuge tubes. Rinse the reactor with 40 milliliters of ethanol and transfer the ethanol to the tubes.

Then vortex the solution for 30 seconds. Centrifuge at 4, 000 G for 15 minutes at room temperature and remove the supernatant. Next, add 10 milliliters of deionized water to each tube and sonicate for five minutes to re-disperse the product.

Add 20 milliliters of ethanol to each tube and vortex for 30 seconds for even mixing. Repeat the centrifugation process and discard the supernatant. Ultra-sonicate the product for five minutes to disperse the product in two milliliters of methanol solution, and store the sample at four degrees Celsius after sealing it with sealing film.

The TEM image showed that zinc germinate manganese PLMPs with pH 9.4 were rod shaped, and had an average diameter of about 65 nanometers. The high resolution TEM images demonstrated that the nanomaterials had good crystallinity, with a lattice spacing of 0.70 nanometers. The afterglow visible emission spectra of the zinc germinate manganese solution showed that the PLNPs exhibited a red shift of the main emission peak when the precursor solution changed from acidic to alkaline.

Additionally, the pH value had an impact on the decay curve of afterglow intensity over time. The photo luminescence images and afterglow images of PMPs revealed that the solution exhibited a brighter green luminescence as the alkalinity of the solution increased. To begin, set the water bath temperature to 80 degrees Celsius.

Add 20 grams of MMA into a dry, 100 milliliter eggplant shaped bottle. Add the pre-prepared methanol solution of zinc germinate manganese with pH 9.4 into the reaction vessel. Seal the reaction to prevent solvent evaporation.

Place the vessel in an ultrasonic-ator for about 10 minutes at room temperature to dissolve the sample in MMA. Next, add 0.012 grams of Azobis isobutyl nitrile to the solution and mix completely. Place the flask in an 80 degree Celsius water bath and purge air with nitrogen for approximately 35 minutes.

Gently shake the container towards the end of the reaction. Quickly transfer the reaction vessel to an ice bath to cool it down after the reaction. Then slowly pour the solution into a two dimensional or three dimensional mold.

Place the mold in an electric thermostatic drying oven set at specific temperatures to obtain the target material. Afterward, close the electric thermostatic drying oven, once the reaction stops, allowing it to cool to room temperature. Open the oven to remove the mold only after it has sufficiently cooled to prevent skin burns.

Carefully demold the polymerized PMMA sample and expose it to a UV lamp for approximately three minutes.