Formation Of MF Spheres And Preparation Of Microspheric Materials With Hollow Or Porous Structure

In recent years, the preparation of organic-inorganic composite microspheres and materials with hollow or porous structure are prepared have been widely concerned. In this paper, MF/SiO2composite microspheres were prepared by the sol-gel method, spray drying method and polymerization-induced colloid aggregation method. Then, a series of materials with hollow or porous structure are prepared by template method. The main content is listed as following:(1) Three different reaction inducing methods, namely the water bath, the microwave irradiation and the Ultrasound irradiation, have been applied to the polymerization of melamine and formaldehyde for the formation of MF spheres. The morphology and the size distribution of the spheres derived from the three different methods have been compared and analyzed. It has been demonstrated that the microwave irradiation and the ultrasound irradiation can induce the polymerization of the intermediate promptly and influence the solubility of the MF spheres in the chloride acid. The influences of the intermediate concentration, the PH value, the dispersant, the reaction temperature and the reaction time on the spheres size and the size distribution have also been studied.(2) By using MF microspheres as the core template and CTAB as the mesoporous directing agents, mesoporous SiO2hollow spheres (SHS) were synthesized via sol-gel method. The obtained SHS materials possess the following characteristics:high specific surface areas contributed mainly by mesoporous with uniform pore size. With the cooperation of TEM, SEM and BET, it was found that the particle size and their surface areas can be varied with adjusting the ratio among TEOS and MF, but the samples intended to aggregate when the ratio up to1:1. The SHS products present excellent adsorption charactors.(3) We have successfully synthesis the MF/SiO2composites via the spray drying technique, and obtained the hollow SiO2spheres after removing the template MF by calcination. The influence of the ratio of colloidal silica and MF on the structures were studied with SEM and TEM. These experimental results could be valuable for the investigation of SiO2hollow spheres by spray drying assisted template method. (4) We demonstrate a facile polymerization-induced colloid aggregation method to synthesize a kind of mesoporous carbon spheres using melamine-formaldehyde resin as a carbon precursor and commercial colloidal silica as a hard template. After the carbonization of as-formed MF/silica composites at800℃under a nitrogen atmosphere, and the removal of silica template by HF treatment, monodisperse mesoporous carbon spheres(MCS) with diameter size of1～2μm, high specific surface area (up to1350m2/g) and uniform pore size as large as25nm can be obtained. Their surface areas can be varied from917.2to1350.7m2/g with adjusting the ratio among melamine resin-formaldehyde and silica. As the electrode nlaterial for supercapacitor, the MCS products present excellent specific capacitance. We suggest that porous carbon has potential application as electrochemical capacitor electrode materials.