Facile Synthesis of Rhodamine B-Doped Poly(3-mercaptopropylsilsesquioxane) Fluorescent Microspheres with Controllable Size

Rhodamine B-doped poly(3-mercaptopropylsilsesquioxane) (RB-PMPSQ) fluorescent microspheres with thiol groups were prepared by a facile sol-gel method. Initially, 3-mercaptopropyltrimethoxysilane (MPTMS) monomer was hydrolyzed in an aqueous acid solution with rhodamine B (RB) as the hydrolysis catalyst and the fluorescent dye at the same time,: and then an ammonia solution was added into the reaction solution to catalyze the condensation reactions of silanol. Through this method, a high yield of RB-PMPSQ fluorescent microspheres with narrow distribution of particle sizes was obtained, and the size of the particles could be effectively controlled depending upon the concentration of the monomer. The morphology and the fluorescent property of RB-PMPSQ microspheres were characterized by scanning electron microscopy (SEM). and fluorescence spectrophotometer, respectively. The fluorescent microspheres showed excellent photostability. The formation mechanism of the fluorescent microspheres was also proposed.