Preparation of holmium doped paramagnetic photoluminescence composite colloidal polymer particles through coordination induced self-assembly

Abstract

Although composite magnetic materials based on iron oxide or ferric oxide have attracted much attention in both basic research and practical applications, the strong visible light absorption always limited their applications as optical or luminescent materials. Here we prepared paramagnetic photoluminescence composite colloidal polymer nanoparticles of P(PEGA)-b-P(AA-co-TPEE) by introducing holmium (Ho) to the assembly. The high magnetic moment of Ho endow paramagnetic behavior to the P(PEGA)-b-P(AA-co-TPEE)/Ho composite particles, and the saturation magnetization value of the P(PEGA)-b-P(AA-co-TPEE)/Ho increased with the increase content of Ho. Owing to the low chroma, Ho has little effect on the light absorption of polymer matrix and would not affect the photoluminescence (PL) behavior of TPEE block in the polymer chains. The coordination of Ho3+ and carboxyl groups decreased the hydrophilicity of PAA blocks, and induced the formation of composite colloidal nanoparticles with different morphologies. Therefore, the relationship between the PL intensity, Ho3+ concentration and saturation magnetization value of the composites could be built. In addition to be paramagnetic photoluminescence composite material, the P(PEGA)-b-P(AA-co-TPEE)/Ho composite particle can be used as a multifunctional carrier for fixed-point release under magnetic field, and can also be used for fluorescence imaging.