Synthesis Of Monodisperse Spherical MCM-41Mesoporous Silica Nanoparticles

Since the discovery of M41S, mesoporous materials exhibit lots of applicationsin catalysis, separation, drug delivery and so on due to many unique properties, suchas extremely high specific surface area, unique pore structure and tunefunctionalization. With the development of preparation of nanotechnology,nanoparticles of mesoporous materials show the increasing prospect of application ingene and drug carriers. If the mesoporous silica nanoparticles (MSNs) were been asan ideal drug and gene carriers, the intrinsical properties of MSNs would be of greatconcern, such as the size of particle, morphology, monodispersity etc. Thus, toexplore the feasible synthetic method of monodisperse spherical MCM-41mesoporous silica nanoparticles have the theoretical and realistic significance.The thesis focuses on two preparation methods of MSNs and the effects ofvarious factors were made a detailed study. On the one hand, the suitable additiveswere put in mixed solution in the synthetic system of urea to improve the quality ofsilica nanoparticles, the size of particles, the formation of uniform morphology andso on using the some characters of additives, including suppression, dispersal andencapsulation. On the other hand, tris (hydroxymethyl) methylamine (Tris)-hydrochloric acid (HCl) buffer solution, as catalyst, which can eliminate thesubstantial change in pH due to the hydrolysis and condensation reaction of siliconspecies, was introduced to prepare the small size of particles, uniform morphologyand high monodispersity. In addition, a series of particles sizes of the monodispersemesoporous silica nanoparticles were synthesized through altering the pH values andtemperature.Used SEM, TEM, XRD, TG and other testing measurements, the researchshowed that the addition of additives greatly reduced the usage amount of urea from9.300g to3.096g. The as-synthesized products had the better XRD diffraction peak,good dispersion and uniform sphere morphology, the sizes of the particles range from75to200nm depending on the amount of ethanol amine, tartaric acid and glycerin. Under the premise of guarantee of particle morphology and monodispersity, the sizeof particles decreased an order of magnitude compared to without additive.Secondly, the MSNs were prepared in the Tris-HCl buffer solution. The resultsshowed that reaction temperature was60℃, pH value within the scope of7.8to8.2,and the reaction time16hours were the best reaction condition for the preparation ofmonodispersed, spherical uniform mesoporous silica materials. In addition, uniformmonodispersed MNSs with ordered pore structure, the particles size was tuned from80to300nm by changing the pH value and reaction temperature. The as-synthesizedmesoporous silica nanoparticles are of significant application in drug and genedelivery systems.