Synthesis and characterization of hydrogel bonded with rare earth

Chitosan-poly(acrylic acid) hydrogel bonded with Eu3+ was prepared by radical solution polymerization. Biodegradable chitosan, N,N′-methylen-diacrylamide, and potassium persulphate were used as the basic material, cross-linking agent, and initiator, respectively. The structure and thermal property of hydrogel were characterized by infrared spectrometry, X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. The swollen property and fluorescent performance were also characterized. The results showed that the rare earth presented unique distribution in the hydrogel due to the formation of chemical bonds after polymerization. The glass transition temperature of the hydrogel decreased remarkably, which might broaden the range of its elastic application considerably. Moreover, the characteristic fluorescent emission of Eu3+ was observed in the hydrogel, which was indicative of the excellent luminescent performance.