Morphology Of Nanoparticles Prepared By Microemulsion Method And Formation Mechanism Discussed

Synthesis of shape controlled is in the forward position of researches and an issue of general interest of multi-disciplines now. Various techniques have been fruitfully employed in the preparation of nanoparticles with different morphologies. The microemulsion-processing method seems to be particularly promising and undergo rapid improvement in the last few years as it does not require special instruments or extreme conditions. However, to the best of our knowledge, the syntheses of nanotubes, nanowires, nanometer whiskers haven't been reported using the nanosized aqueous channels in the bicontinuous microemulsion as templates. Few researchers discussed the formation mechanism of nanoparticles with different morphologies in microemulsion. It is significant to make an explorative investigation on preparing nanoparticles with different morphologies in microemulsion systems. The main contents of this paper are shown as below.(1) The PbS nanoparticles were prepared in quaternary system containing P-Octyl polyethylene glycol phenylether (OP)/n-pentanol/ cyclohexane/ aqueous solution by different homogenization methods, such as shake by hand , stir by machine and disperse by ultrasonic. The microstructure , particle size , morphologies and properties of PbS were characterized by means of X-ray diffraction (XRD) , transmission electron microscopy (TEM) and ultraviolet-visible (UV-vis) absorption spectroscopy. The results show that different homogenization methods have no effect on the microstructure except the particle size and morphologies of PbS nanoparticles. The UV-vis absorption spectra of PbS nanoparticles exhibit a blue shift in the absorption edges of the samples compared with that of bulk PbS, indicating the quantum size effect of PbS nanoparticles.(2) PbS nanoparticles with different morphologies, such as shuttle-like, rod-like , needle-like and spherical, were prepared in W/O microemulsion containing non-ionic surfactant OP, iso-octyl alcohol ( or n-pentanol ), Cyclohexane and aqueous solution. The structures and morphologies of the PbS nanoparticles were characterized by XRD and TEM. The influences of w0 (molar ratio of water to surfactant), the concentration of the reactants and the aging time on the morphologies and the sizes of the nanoparticles were studied. The formation mechanisms of PbS nanoparticles withdifferent morphologies in W/O microemulsion were discussed.(3) PbS nanotubes, CaC2O4 nanowires and CaCO3 nanometer whiskers were first synthesized in the bicontinuous microemulsion containing non-ionic surfactant OP/n-pentanol/cyclohexane/aqueous solution. In those processes, the nanosized aqueous channels in the bicontinuous microemulsion were used as sofe templates. The influences of different experimemtal conditions on the morphologies of nanoparticles were investigated. The formation mechanisms of nanoparticles with different morphologies in the bicontinuous microemulsion were also discussed.