Structural comparison of hexagonally ordered mesoporous thin films developed by dip- and spin-coating using X-ray reflectometry and other quantitative X-ray techniques

摘要

Clear and homogeneous precursors for casting mesoporous thin films (MTFs) were prepared by addition of a triblock polyalkylene oxide amphiphilic surfactant (the structural directing agent) to a clear sol of tetraethylorthosilicate.Films were developed by dip- and spin-coating methods and calcined to yield high quality crack-free coatings containing highly ordered hexagonal arrangements of mesopores.Comparison of the dip-coating and spin-coating methods was made using X-ray methods including powder X-ray diffraction,reciprocal space mapping,X-ray reflectometry and in-plane scattering.In all cases,the films had a highly textured nature with preferential alignment of pores parallel to the substrate.It was found that the dip-coating method resulted in better quality films with greater long range order.The varied X-ray methods provided a detailed structural analysis of the mesoporous thin films which showed a distorted hexagonal arrangement.The results defining pore size could be directly and favourably compared to TEM and N_2 isotherm data.It was found that all the techniques are in reasonable agreement.