Synthesis of CdS/SiO/polymer tri-layer fluorescent nanospheres with functional polymer shells.

Tri-layer CdS/SiO/polymer hybrid nanospheres were synthesized by distillation precipitation polymerization of either ethyleneglycol dimethacrylate (EGDMA) or EGDMA together with comonomers having different functional groups, such as methacrylic acid, 4-vinylpyridine and 2-hydroxyethylmethacrylate, in the presence of 3-(methacryloxy)propyl trimethoxysilane (MPS)-modified CdS/SiO nanoparticles as seeds in acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as initiator. In this approach, MPS-modified inorganic seeds were prepared by the modification of CdS/SiO nanoparticles via the self-condensation reaction between the hydroxyl groups of sinaols, in which the CdS/SiO nanoparticles were afforded by a reverse microemulsion technique for the synthesis of CdS core nanoparticles with the subsequent coating of silica layer. The polymer shell-layers encapsulated over the MPS-modified CdS/SiO inorganic seeds via the efficient capture of the monomers and oligomers from the solution with the aid of the vinyl groups incorporated by the MPS modification, in which the polymer shell-thickness and functional groups including carboxyl, pyridyl and hydroxyl, were facilely controlled by the feed of EGDMA as well as the types of comonomers used for the polymerization. These nanospheres were characterized by transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), fluorescence spectroscopy and zeta potential. [ABSTRACT FROM AUTHOR]