[Synthesis and fluorescence properties of thermo-responsive microgel nanoparticles]

In the present paper, the preparation and properties of Eu(III) on poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-co-AAc)) were described. At first, P(NIPAM-co-AAc) microgel nanoparticles were prepared by the precipitation copolymerization of N-isopropylacrylamide with acrylic acid in the presence of N, N-methylenebisacrylamide in water. The morphology and size of the P(NIPAM-co-AAc) nanoparticles were characterized by the scanning electron microscope (SEM) method. The result of SEM shows that the sample is uniformly sized spherical particle and the average particle size of the P(NIPAM-co-AAc) is about 365 nm. Then, EuCl3 was chosen to interact with P(NIPAM-co-AAc) nanoparticles and formed the complex of P(NIPAM-co-AAc)-Eu(III). The complex was characterized by Fourier transform infrared spectroscopy, ultraviolet-visible and fluorescence spectroscopy. It was found that the complex shows thermo-responsive fluorescence from the experimental results. There exists a energy transfer between the polymer ligand and the Eu(III), which can enhance fluorescence emission of the polymer ligand and Eu(III) at the same time. The LCST of P(NIPAM-co-AAc) containing Eu(III) has changed little after the formation of the complex of P(NIPAM-co-AAc)-Eu(III). Therefore, the complex can be used for developing the new applications in biomedical and fluorescence field.