Regensburg 2007 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 20: POSTER: Biological Systems + New Materials
CPP 20.20: Poster
Wednesday, March 28, 2007, 16:00–18:30, Poster B
Spontaneous onion formation from planar lamellar nuclei — •Yasutaka Iwashita1 and Hajime Tanaka2 — 1Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany — 2Institute of Industrial Science, University of Tokyo, Tokyo, Japan
Onion phase, which is composed of multilamellar vesicle (MLV, or onion) structures in lyotropic liquid crystals, has been studied in its formation under shear flow since the discovery by Roux et al. in 1993. However it has been also reported that onion phase can be formed spontaneously via sponge (isotropic)-to-lamellar phase transition without shear when lamellar phase nucleates as onions. In this study we report a new interesting step of the lamellar ordering (nucleation) from the sponge phase observed directly with optical microscopy: Initially lens-shaped nuclei (planar lamella) nucleate, and then they spontaneously transform into onion nuclei. We also reveal that the origin of this shape transformation is the competition between curvature elastic and interfacial energy. This means a remarkable fact that the initial most stable bulk structure (planar lamella) spontaneously changes into the metastable higher-energy bulk structure (onion). Finally we mention the aspect as a novel ordering step peculiar to a system of low-dimensional internal order (layered structure): The fate of nuclei can be seriously affected by the competition between interfacial and elastic deformation energy in general.