Droplet-filament-membrane-vesicle-double vesicle spontaneous transformations in nematosmectogen NPOOB/silicone oil systems

Abstract

Multiphase germs of various geometry are formed at the phase transition from the isotropic melt to the mesomorphic phase in many multicomponent systems containing both nematogen and smectogen components, or one at least nematosmectogen (adopting both nematic and smectic phases). The germs evolve spontaneously from thin plates arising as the first stage, to rolled-up polygons, and to highly elongated heterostructural filaments which then undergo immediate shrinkage to droplets, followed by segmentation, splitting along the axis, double-spiralling and encapsulation up to vesicles. In the present work, a quite similar chain of events is reported for a two-component system composed of the pure nematosmectogen 4-nitrophenyl-4′-octyloxybenzoate (NPOOB) dissolved in inert silicone oil H. These phenomena include (i) phase separation giving liquid-crystalline thin films in the bulk or on the surface of the silicone oil, (ii) rolling-up of the films to initial polygons or droplets, (iii) production of highly elongated filaments extracted from inside the rolled-up polygons or droplets, (iv) cross-wise splitting of the filaments to form framed membranes, (v) encapsulation of the framed membranes to spheroidal vesicles, (vi) budding of secondary filaments from inside the vesicles, (vii) splitting of the secondary filaments and (viii) formation of secondary vesicles connected with the primary vesicles. The phase separations and capillarity processes involved in these phenomena are discussed.