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  Abbott Research Group - UW Chemical and Biological Engineering

Laboratory for Molecular Engineering
Department of Chemical and Biological Engineering

Aqueous - Liquid Crystal Interfaces

Reported the preparation of polymeric capsules by a template-based synthesis method that employs monodisperse silica spheres (with diameters of 0.7, 1, 3, 5, 8, and 10 micrometers), and the filling of these capsules with a nematic LC, thus forming polymer-coated LC droplets (Chem. Mater., 2008). This approach provides a level of control over size and interface-dependent ordering of LC droplets that has not been possible in the past, reveals size-dependent changes in topological ordering not anticipated by theoretical considerations, resolves varying observations reported in the literature, and will enable size-dependent properties of LC droplets to be exploited in applications such as photonics and sensing (Angew. Chem. Int. Ed., 2009).

Schematic illustration of the preparation of LC droplets of predetermined sizes (10um to 700nm) within polymeric multilayer shells using a template based technique. Droplets of different sizes are used to report the size dependent ordering of liquid crystal with polymeric capsules.A)Preparation of LC droplets of predetermined sizes within polymeric multilayer shells. Polymeric shells were prepared by sequential deposition of PSS and PAH onto silica templates and subsequent etching of the silica (see also Figure S1 in the Supporting Information). The resulting polymeric shells were filled with LCs. B, D, G, I, L) Bright-field micrographs of polymer-encapsulated 5CB droplets obtained using silica templates with diameters of 10 ± 0.22 μm, 8 ± 0.20 μm, 5 ± 0.19 μm, 3 ± 0.18 μm, 1 ± 0.04 μm, and 0.7± 0.08 μm, respectively. C, F, H, K) Polarized light micrographs (crossed-polarizers) corresponding to B, D, G, I, L respectively. E, J, M) Illustration of the transition in director alignment of 5CB associated with decreased LC droplet diameter. The scale bars in all images correspond to 3 μm.