Study On The Interaction Between P(NIPAM-co-AAc) Microgel Nanoparticles And Rare Earth Ions

As a kind of temperature-sensitive material, the application of poly (N-isopropylacrylamide) (PNIPAM) nanoparticle has been paid much attention in recent years. In order to obtain multi-sensitive hydrogels, many studies were focused on theoretic explanation of the stimuli-response mechanism and the copolymerization of NIPAM with other monomers to modify their properties, which can be used to develop the new applications in the biomedical and fluorescence field.Based on the synthesis of P(NIPAM-co-AAc) microgel nanoparticles by the precipitation copolymerization of N-isopropylacrylamide with acrylic acid in the presence of N,N'-methylenebisacrylamide (Bis) in water, a new kind of the complex of rare earth ions (Terbium, Europium) and P(NIPAM-co-AAc) with the novel temperature-responsive, pH and fluorescence properties was successfully prepared and characterized with different techniques. The main results obtained are as follows:1. Effects of Bis on the P(NIPAM-co-AAc) microgel nanoparticles form was investigated systematically. Then, microgel nanoparticles were prepared under optimum conditions. The pH and temperature sensitivity of the microgcls were characterized by the transmittance of microgcl suspensions as function of temperature and pH. The low critical solution temperature (LCST) of microgel solution was influenced by the content of AAc in microgel polymer significantly. LCST of microgel increased with the content of AAc of hydrophilic properties increasing. However, after incorporation AAc in the PNIPAM, the P(NIPAM-co-AAc) microgel became pH sensitivie. In addition, with AAc amount in the copolymer increasing, such pH-sensitivity enhanced.2. The research interest of this thesis is concentrated on temperature-responsive, pH and fluorescence properties of rare earth ions (Terbium, Europium) and P(NIPAM-co-AAc), and the research work were carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Zeat, ultraviolet-visual (UV-vis) absorption spectroscopy, fourier transform infrared spectroscopy(FTIR) and fluorescence spectroscopy. It was found from the experimental results that there exits a energy transfers between the polymer ligand and the Tb(III), it can enhance fluorescence emission of the Tb(III), the intramolecular energy transfer efficiency from P(NIPAM-co-AAc) to Tb(III) reached 40%. the complex shows thermo-responsive, pH-responsive properties; There exits a energy transfers between the polymer ligand and the Eu(â…¢) , it can enhance fluorescence emission of the polymer ligand and Eu(â…¢) at the same time. The LCST of P(NIPAM-co-AAc) containing Eu(â…¢) has changed little after the formation of the complex of P(NIPAM-co-AAc)-Eu(â…¢).