Effect of Tb(III) on the properties of P(NIPAM-co-St) copolymer microspheres

Based on the synthesis of copolymer microspheres of N-isopropylacrylamide (NIPAM) and styrene (st) (P(NIPAM-co-St)), the interaction of Tb(III) and P(NIPAM-co-St) was investigated. It was found that when Tb(III) interacts with P(NIPAM-co-St) Tb(III) mainly bonds to O of the carbonyl group of P(NIPAM-co-St), forming the novel P(NIPAM-co-St)-Tb(III) complex. LCST, the zeta potential and the emission fluorescence intensity of P(NIPAM-co-St)-Tb(III) complex are different from P(NIPAM-co-St). Especially, after forming the complex, the intensities of the emission fluorescence peaks of Tb(III) at 487, 544 and 585 nm are enhanced 34, 35 and 17 times, respectively, comparing with that of the corresponding peaks of TbCl₃. Therefore, the P(NIPAM-co-St)-Tb(III) complex could transform the harmful ultraviolet radiation to harmless visible light. It is hoped that the results will provide a reference point for new applications of complexes of polymers and rare-earth elements, such as the P(NIPAM-co-St)-Tb(III) complex, in biomedicine and fluorescence systems.