Facile synthesis of near white light emitting polymeric nanoparticles based on Schiff-base networks

Abstract

Polymeric nanoparticles with near white fluorescence were prepared from melamine and glyoxal through solvothermal reaction in a single step. The colour of the fluorescence of the products was excitation wavelength dependent, which was near white under UV irradiation and gradually shifted to red when excitation wavelength shifted from 300 nm to 570 nm. The influence of the preparation conditions on the fluorescence intensity was investigated and the morphology of the products was confirmed by HRTEM and AFM. The size of the particles was mainly in 30–80 nm range. A quantum yield of 22% could be achieved under the optimum condition. FTIR and NMR indicated that the products were typical Schiff-base networks. Effect of solvents on the fluorescence property was also examined and the strongest emission was obtained in DMSO. To verify the origin of the different colour of the fluorescence, the products were analyzed using electrophoretic methods and the results indicated that dependence of the emission colour was not correlated to the variation of the particle size. The possible origin of the fluorescence was also proposed and the products can be non-toxic alternatives of inorganic quantum dots for white light emission.