The crystallization of calcite from mixed alcohol water solvents in the presence of a double hydrophilic block copolymer poly(ethylene glycol) block poly(methacrylic acid)(PEG b PMAA) has been investigated. It was rev...The crystallization of calcite from mixed alcohol water solvents in the presence of a double hydrophilic block copolymer poly(ethylene glycol) block poly(methacrylic acid)(PEG b PMAA) has been investigated. It was revealed that with increasing the volume fractions of ethanol or isopropanol, the morphology of the CaCO 3 particles generally varies from peanuts through rods to spheres in the presence of the polymer. Specifically, uniform rounded calcite rods, which are about 2 μm in length with an aspect ratio of 2.6, were obtained in the isopropanol solution with volume fraction 50%.展开更多
Silica particles with rod-like and top-like morphologies have been controllably synthesized with a basic medium. The characteristics of the mesoporous silica particles were characterized by X-ray diffraction (XRD), ni...Silica particles with rod-like and top-like morphologies have been controllably synthesized with a basic medium. The characteristics of the mesoporous silica particles were characterized by X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The results indicate that temperature affects the macrostructures and mesostructure ordering of mesoporous silica. At lower temperature highly ordered mesoporous silica with hexastyle and top structure could be obtained under different alkalinity. As the temperature increases, mesoporous silica transforms to a rod-like shape and the aspect ratio of length/diameter decreases with the decrease of the order of mesostructure. When the temperature is high enough, spherical particles could be prepared and there are still defects existing in mesostructure.展开更多
文摘The crystallization of calcite from mixed alcohol water solvents in the presence of a double hydrophilic block copolymer poly(ethylene glycol) block poly(methacrylic acid)(PEG b PMAA) has been investigated. It was revealed that with increasing the volume fractions of ethanol or isopropanol, the morphology of the CaCO 3 particles generally varies from peanuts through rods to spheres in the presence of the polymer. Specifically, uniform rounded calcite rods, which are about 2 μm in length with an aspect ratio of 2.6, were obtained in the isopropanol solution with volume fraction 50%.
文摘Silica particles with rod-like and top-like morphologies have been controllably synthesized with a basic medium. The characteristics of the mesoporous silica particles were characterized by X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The results indicate that temperature affects the macrostructures and mesostructure ordering of mesoporous silica. At lower temperature highly ordered mesoporous silica with hexastyle and top structure could be obtained under different alkalinity. As the temperature increases, mesoporous silica transforms to a rod-like shape and the aspect ratio of length/diameter decreases with the decrease of the order of mesostructure. When the temperature is high enough, spherical particles could be prepared and there are still defects existing in mesostructure.
