Preparation And Characterization Of Mesoporous Silica Materials

Synthesis of ordered mesoporous silica materials began in1970.Mesoporous silicamaterials are the inorganic biomaterials with ultra-high surface area，large pore volume，controlled shape and size，which have attracted wide attention because of theirapplication in biomedicine.Mesoporous silica nanomaterials with very high chemicalstability， biocompatibility， low cost and ease synthesis are provided with both the dualcharacteristics of mesoporous materials and nano-materials.In recent years，with moreand more applications in biomedicine，the researches of mesoporous silica mainly focuson new synthesis，synthesis of new micro structure and analytical test，etc.For now，hydrothermal synthesis method is still the main method to prepare mesoporous silica.Butit takes much time(at least10more hours) and is hard to operate.From the above，themain task to synthesise mesoporous silica is to shorten time and to simplify the progress.This paper introduces the synthesis method and characterization technique ofmesoporous SiO2.After the introduce，mesoporous SiO2is prepared by hydrothermalsynthesis method.The micro-structure of these SiO2is inerratic and ordered.The progressof hydrothermal synthesis method for mesoporous SiO2is simplified for only about10hours，simple operation and satisfying results.The characterization of samples includes Small Angle X-ray Diffraction(SAXRD)，Fourier Transform Infrared Spectrum(FT-IR)，Nuclear Magnetic Resonance(NMR) andTransmission Electron Microscope(TEM)，etc.Micro-structure and synthesis mechanismare analysed.Mesoporous matericals can be controlled by changing acidity andtemperature.The influences of different acidities and temperatures on size，morphologyand structure of mesoporous SiO2are studied.The main results are as follows:(1)Hydrothermal synthesis method prepared inerratic and ordered in long-range nanomesoporous SiO2，shortened reaction time，simplified operation.SAXRD，FT-IR，NMRand TEM were used to characterize the samples.Through above characterizations，themicro-structure of samples can be observed.Thus，this paper analyzed the chemical bond，pore canal structure and synthesis mechanism.(2)With hydrothermal synthesis，different pore size and pore-size diffraction ofmesoporous SiO2can be obtained by changing acidity.When the condensation of acid is2mol/L or1mol/L，the mesoporous SiO2are in parallel arrangement and high-ordered.Thedistance between neighbouring pore centers is6or7nm.When the condensation of acidis0.5mol/L，the order of mesoporous SiO2gets down in part.The distance betweenneighbouring pore centers is about8nm.When the condensation of acid is0.1mol/L，thearrangement of mesoporous SiO2is HMS.The distance between neighbouring porecenters is about9nm.When the condensation of acid is0.01mol/L，the order ofmesoporous SiO2pore gets down quickly and becomes disorderly.When the condensationof acid is0.001mol/L，the disorderly pores basicly disappear，mesopores won’t form.Thestructure of SiO2is no longer mesoporous.(3)In the progress， changing the calcination temperature can influence themicro-structure of SiO2.When the temperature is550℃，the pores of mesoporous SiO2are better long-range ordered.The diameter is6-7nm，and pore wall is about1.0nm.When the temperature is500℃，the long-range order gets down，some SiO2structures tend to be disorderly，other area is still ordered.The diameter is7-8nm，andpore wall is about1.0nm.When the temperature is450℃，most of the SiO2structurestend to be disorderly，defects appear in some area.The diameter is about9nm.