Investigation Into Synthesis Of Monodisperse MCM-48 Mesoporous Nanoparticles With The Spherical Morphology

The M41S family of mesoporous molecular sieves has attracted considerable attention because of its uniform pore size distribution, large surface area and pore volume, and perfect long range order. These materials have been widely used in many fields such as catalysis, adsorption and separation. MCM-48 seems to be more attractive than MCM-41 in molecular delivery, since its three dimensional channel networks provide more favorable mass transfer kinetics and then avoid pore blockage. Thus, all those characteristics promise MCM-48 endorsed as lead candidates for host matrices of biomedical in the next generation. However, up to now, the MCM-48 synthesized by traditional method is irregular morphologies, particle size is too large and the dispersity is poor. Therefore, exploring a new synthesis pathways is of great significance.In this thesis, the MCM-48 was prepared with two preparation methods. The first method was room temperature synthesis. Cetyltetramethylammonum bromide (CTAB) and non-ionic surfactant F127 were applied as a template and a dispersion agent, respectively. Meanwhile, we investigated the influence on the particle size and morphology of products with different amounts of F127. And The second way of preparing MCM-48 was established with combined sol-gel technology with homogeneous deposition method.The CTAB, urea and TEOS were applied as a template, catalyst and silica source, respectively. During the synthesis procedure we investigated the influence factors on the structure and morphology of products, such as CTAB/TEOS and urea/TEOS molar ratios and reaction temperature, reaction times. Finally the products prepared by the two methods were characterized by XRD, SEM, TEM, TGA, FT-IR and N2 adsorption-desorption.The results showed that the MCM-48 with particles size of 400-500nm is obtained by room temperature synthesis. As to the sol-gel with homogeneous precipitation synthesis, the XRD reveals that the MCM-48 has good structural order, the SEM and TEM reveal that the sample is composed of uniform particles which are both in size (120-150nm) and shape (sphere). The specific pore volume, BET surface area and average pore diameter of the product are 0.78cm3/g,588.36m2/g,2.50nm respectively. The optimum reaction conditions as following:the system was reacted under the refluxed condition at 95℃ for 9.Oh, The molar composition of the system was TEOS:CTAB:urea=1:0.15:12.5.