Size-Dependent, Surface-Induced Ordering of Liquid Crystals Observed in Monodispersed Droplets with Micrometer-to-Nanometer Sizes

Mon, 16 Mar 2009 15:01:38 -0500

Representative configuration of mesogens confined within spherical LC droplets with nanometer-scale dimensions, as predicted by simulations. The top figures show cross-sections of the droplets. The bottom figures show the interfaces of the droplet in contact with water (red), which promotes parallel anchoring, and surfactant molecules (green) that promote homeotropic anchoring. At elevated temperatures, the mesogens and surfactant adopt disordered configurations, whereas upon lowering the temperature, the mesogens exhibit nematic ordering and the surfactant at the interface adopts an ordered morphology consisting of regular stripes.

Jugal K. Gupta, S. Sivakumar, Frank Caruso, Nicholas L. Abbott (DMR #0520527)[Image386]It is widely appreciated that the supramolecular ordering of polymers, surfactants and liquid crystals (LCs) can be impacted by confinement. In many cases, however, these effects remain poorly understood. This is particularly true for LCs, where confinement-induced ordering in natural systems (e.g., containing DNA and proteins) underlies remarkable material properties such as the strength of spider silk,....

Nanoimprinted Thin Films of Reactive, Azlactone-Containing Polymers: New Methods for the Topographic Nanopatterning with Facile Post-Fabrication Chemical Functionalization

Mon, 16 Mar 2009 14:54:16 -0500

Schematic illustrations of (A) transfer of nano- and micrometer-scale topographic features to a thin film of a reactive, azlactone-containing polymer using nano-imprint lithography (NIL), and (B) post-fabrication chemical modification of azlactone functional groups by reaction with amine-functionalized nucleophiles. (C) Structures of the reactive, azlactone-containing homopolymer and copolymer used in this study. (D,E) Phase contrast (D) and fluorescence microscopy (E) images of NIH-3T3 fibroblasts (stained with calcein AM) seeded on a film of azlactone-containing polymer imprinted with a pattern of lines at a 4-µm pitch. The dotted arrows indicate the direction of the topographic features. Scale bars = 100 µm (25 µm for inset).

Nathaniel J. Fredin, Adam H. Broderick, Maren E. Buck, David M. Lynn (DMR #0520527)Approaches to the fabrication of surfaces that combine methods for the topographic patterning of soft materials with opportunities for facile, post-fabrication chemical functionalization will contribute significantly to advances in the design of a broad range of functional materials, including biomaterials. IRG3 has developed new methods that can be used to introduce well-defined topographic features into....

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Size-Dependent, Surface-Induced Ordering of Liquid Crystals Observed in Monodispersed Droplets with Micrometer-to-Nanometer Sizes

Nanoimprinted Thin Films of Reactive, Azlactone-Containing Polymers: New Methods for the Topographic Nanopatterning with Facile Post-Fabrication Chemical Functionalization