Preparation Of Oriented Mesoporous Films By Hot Air Flow And Study Of Their Preliminary Applications

With ordered mesostructures, relatively large surface area, and low dielectricconstant, ordered mesoporous films with oriented mesochannels have presented greatpotential of applications in many fields such as adsorption and separation, magnetic,optics, microelectronics and etc. The alignment of mesochannels in films and itscontrol are quite important to these applications. In this thesis, we investigated thepreparation of oriented mesoporous films with mesochannels aligned in a desireddirection. Using the mesoporous silica film with parallelly oriented mesochannels ashost, we further introduced gold nanoparticles and gold nanowires into themesochannels to form the Au-mesoporous silica hybrid films. The third non-linearoptical properties of such hybrid films was also investigated. The details are asfollows:(1)The hot air flow method was employed to prepare oriented mesoporous silicafilms. Adjust the alignment of mesochannels via manipulation of the preparationconditions, like the air flow rate, incident angle and the viscosity of sol precursorsolution. The structure of mesochannels was detected by SAXRD, in-Plane XRD,TEM and GISAXS. The orientation of the mesochannels can be regulated fromparallel orientation to tiled orientation with ordered mesostructure. In particular, thetilted orientation with inclination angle of42°is obtained at the air flow rate of5.5m/s and incident angle of50°. The electrochemical property of the mesoporousfilm with such tilted mesochannels shows an effective charged molecular transportacross the film.(2)Gold nanoparticles or gold nanowires were introduced into the mesochannelsof the parallel oriented mesoporous films to form Au-mesoporous silica compound films. Both in the water system and ethanol system, we prepare gold nanoparticles ornanowires via reduction of NaBH4. With trying different reducing agents, we find thatthe obtained gold nanoparticles are more homogenous in size, have betterdispersibility and also the integrity of the ordered structure of the mesoporous film aremaintained by NaBH4-ascorbic acid reducing agent. And gold nanowires are preparedby reduction of H2. Additionally, obvious non-linear optical properties of the goldnanowires-mesoporous silica film were testified by Z-scan measurement and theyshow anisotropy.