Photo-orientation of mesoporous silica materials via transfer from an azobenzene-containing polymer monolayer

Abstract

Successful photo-orientation of mesostructured surfactant/silica hybrids is performed via hierarchically relayed multiple transfers among hetero-interfaces. A Langmuir–Blodgett monolayer of the azobenzene-containing polymer was first optically oriented via irradiation with linearly polarized light, and the photoinduced anisotropy of this layer was then transferred and fixed to a thin film of polysilane [poly(di-n-hexylsilane), (PDHS)]. The Si backbone of PDHS is aligned perpendicular to the polarization plane of the light, which is in accord with the direction of the photoaligned azobenzene monolayer. On this photoaligned polymer surface, the sol–gel process from the precursor with surfactants was performed. The photo-orientated mesochannels had a preferential orientation perpendicular to the direction of the pre-irradiated actinic polarized light over the whole plane when PDHS (M_w = 4.5 × 10⁴) was used for the preparation. The mixture of a liquid crystal and a dichroic dye can be incorporated into the mesochannels by capillary action. The photo-oriented mesochannels produced an anisotropic alignment of the incorporated dye. The alignment of functional molecules in the uniaxially aligned mesochanneled film may lead to new technological aspects.