Synthesis and properties of multi-layer core-shell Tb(BAO)3(NO3)2@SiO2@(PSPEA-PMMA) microsphere with photoluminescence and photochromic functions

Multi-functional microspheres with core-shell structure are playing an important role in the preparation of multi-functional materials due to their large specific surface and nanoscale dispersion of functional units. According to the design of the core-shell structure, the nuclear layer with good photoluminescence function and thermal stability, Tb(BAO)3(NO3)2@SiO2, was prepared by synchronous co-catalytic precipitation technology. The average particle size of as-prepared the Tb(BAO)3(NO3)2@SiO2 is 252 nm. The fluorescence intensity and fluorescence lifetime can reach 5.1 × 107 a.u. and 1141 μs, respectively. The polymers units with photochromic function were introduced into the surface of the as-prepared Tb(BAO)3(NO3)2@SiO2 nanoparticles by modification of the amino groups and grafting polymerization. The Tb(BAO)3(NO3)2@SiO2@(PSPEA-PMMA) can show obvious photochromic function after being irradiated by UV light for 60 s. Even in the darkroom, Tb(BAO)3(NO3)2@SiO2@(PSPEA-PMMA) can also maintain its photochromic color for 2–3 h. The fade process can be completed within 2 min through the far infrared lamp irradiation. The results of fluorescence spectrum further reveal that Tb(BAO)3(NO3)2@SiO2@(PSPEA-PMMA) not only has the good photochromic function, but also maintains good photoluminescence function. The as-prepared multi-layer core-shell Tb(BAO)3(NO3)2@SiO2@(PSPEA-PMMA) microsphere can displayed in milky white, green, red, yellow and purple under different excitation lights. This paves a way for the design and development of multifunctional photoluminescence materials.