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Item type:Publication, Access status: without files , Structure and phase behavior of a discotic columnar liquid crystal confined in nanochannelsThe confinement of discotic columnar liquid crystal in nanoporous templates is a promising strategy to design nanofibers with potential applications in organic electronics. However, for many materials, geometric nanoconfinement has been shown to induce significant modifications of the physical properties, such as structure or phase behavior. We address the case of a discotic columnar liquid crystal confined in various templates. The influence of the size, the roughness, and the chemical nature of pores was investigated for a pyrene derivative by small-angle neutron scattering, X-ray diffraction, and calorimetry on a wide range of temperatures. A homeotropic anchoring (face-on orientation of the disk-shape molecules at the interface) is favored in all smooth cylindrical nanochannels of porous alumina while surface roughness of porous silicon promotes more disordered structures. The hexagonal columnar-isotropic phase transition is modified as a result of geometrical constraints and interfacial interactions.Publicationtype: Journal Article38 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Rich polymorphism of a rod-like liquid crystal (8CB) confined in two types of unidirectional nanopores(Springer, 2008-05-29); ; ; ; We present a neutron and X-rays scattering study of the phase transitions of 4-n-octyl-4' -cyanobiphenyl (8CB) confined in unidirectional nanopores of porous alumina and porous silicon (PSi) membranes with an average diameter of 30nm. Spatial confinement reveals a rich polymorphism, with at least four different low temperature phases in addition to the smectic A phase. The structural study as a function of thermal treatments and conditions of spatial confinement allows us to get insights into the formation of these phases and their relative stability. It gives the first description of the complete phase behavior of 8CB confined in PSi and provides a direct comparison with results obtained in bulk conditions and in similar geometric conditions of confinement but with reduced quenched disorder effects using alumina anopore membranes.Publicationtype: Journal ArticleScopus© Citations 36 14