A skeletal double gyroid formed by single coaxial bundles of catechol based bolapolyphiles

2018 ◽  
Vol 54 (79) ◽  
pp. 11196-11199 ◽  
Author(s):  
Silvio Poppe ◽  
Changlong Chen ◽  
Feng Liu ◽  
Carsten Tschierske
Keyword(s):  
Cubic Phase ◽  
Rod Bundles ◽  
Double Gyroid

A new cubic phase is reported, formed by two networks of rod-bundles with one molecule length and containing discrete polar aggregates at the junctions.

Liquid Crystalline Nano-Segregated Structures in Hydrogen-Bonded Complexes of Fluoroalkyl Substituted Benzoic Acids

2001 ◽  
Vol 709 ◽  
Author(s):  
Etsushi Nishikawa ◽  
Jun Yamamoto ◽  
Hiroshi Yokoyama
Keyword(s):  
Phase Transition ◽  
Liquid Crystalline ◽  
Cubic Phase ◽  
Benzoic Acid Derivatives ◽  
Smectic C ◽  
Texture Change ◽  
Double Gyroid ◽  
Substituted Benzoic Acids ◽  
Bonded Complexes ◽  
Hydrogen Bonded

ABSTRACTSeveral new benzoic acid derivatives having perfluorinated substituents were synthesized and their hydrogen-bonded complexes with 4, 4’-dipyridyl were prepared. In these acid/base complexes the incompatibility between perfluoroalkyl moieties and hydrocarbon parts is large, which can lead to organize nano-segregation structures. We have found in one of such complexes, that has a long flexible fluorinated moiety, a thermotropic cubic phase with Ia3d symmetry formed by double gyroid of two interpenetrating jointed rod networks with an estimated cell parameter of 10.9 nm. Furthermore another complex with a branched long perfluoroalkyl terminal chain exhibits a first order smectic A to smectic C phase transition, which is confirmed with thermal analysis detecting a large enthalpy change of 5.3 kJxmol-1, X-ray scattering experiments revealing a tilt angle jump, and polarized optical microscopy observing a remarkable texture change at the phase transition temperature.

Tricontinuous Double Gyroid Cubic Phase in Triblock Copolymers of the ABA Type

1997 ◽  
Vol 30 (19) ◽  
pp. 5634-5642 ◽  
Author(s):  
Apostolos Avgeropoulos ◽  
Benita J. Dair ◽  
Nikos Hadjichristidis ◽  
Edwin L. Thomas
Keyword(s):  
Triblock Copolymers ◽  
Cubic Phase ◽  
Double Gyroid

Epitaxial Phase Transformation between Cylindrical and Double Gyroid Mesophases

2004 ◽  
Vol 856 ◽  
Author(s):  
Lei Zhu ◽  
Lu Sun ◽  
Jianjun Miao ◽  
Li Cui ◽  
Qing Ge ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Small Population ◽  
Significant Loss ◽  
Cubic Phase ◽  
Cubic Phases ◽  
Transmission Electron ◽  
Bicontinuous Cubic ◽  
Double Gyroid ◽  
Poly Ethylene ◽  
Unit Cell Dimensions

ABSTRACTComplex phase transformation between the hexagonal cylinder (Hex) and double gyroid (G) phases in a polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer was investigated using two-dimensional (2D) synchrotron small-angle X-ray scattering (SAXS), and transmission electron microscope (TEM). The PS-b-PEO sample contained a small population of another bicontinuous cubic phase having an Im3m symmetry. These two bicontinuous cubic phases (G and Im3m) had the same unit cell dimensions. Under a large-amplitude reciprocating shear, the bicontinuous cubic phases transformed into a “single-crystal”-like Hex phase. When annealed at 150 °C for 40 min, the Hex phase partially transformed into well-oriented twinned structures of the G and Im3m phases without significant loss of orientation in 2D SAXS measurements. Epitaxial phase transformation relationships between the Hex/G and Hex/ Im3m phases were identified. The mechanism of the Hex → G transformation was examined by TEM.

Use of fractals to describe microstructures of porous thick-film platinum electrodes

1992 ◽  
Vol 50 (1) ◽  
pp. 314-315
Author(s):  
Steven D. Toteda
Keyword(s):  
Fractal Dimension ◽  
Power Plants ◽  
Electrical Response ◽  
Cubic Phase ◽  
Platinum Electrodes ◽  
Fine Grained ◽  
Impedance Response ◽  
Platinum Particles ◽  
Energy Surfaces ◽  
Highly Porous

Zirconia oxygen sensors, in such applications as power plants and automobiles, generally utilize platinum electrodes for the catalytic reaction of dissociating O2 at the surface. The microstructure of the platinum electrode defines the resulting electrical response. The electrode must be porous enough to allow the oxygen to reach the zirconia surface while still remaining electrically continuous. At low sintering temperatures, the platinum is highly porous and fine grained. The platinum particles sinter together as the firing temperatures are increased. As the sintering temperatures are raised even further, the surface of the platinum begins to facet with lower energy surfaces. These microstructural changes can be seen in Figures 1 and 2, but the goal of the work is to characterize the microstructure by its fractal dimension and then relate the fractal dimension to the electrical response. The sensors were fabricated from zirconia powder stabilized in the cubic phase with 8 mol% percent yttria. Each substrate was sintered for 14 hours at 1200°C. The resulting zirconia pellets, 13mm in diameter and 2mm in thickness, were roughly 97 to 98 percent of theoretical density. The Engelhard #6082 platinum paste was applied to the zirconia disks after they were mechanically polished ( diamond). The electrodes were then sintered at temperatures ranging from 600°C to 1000°C. Each sensor was tested to determine the impedance response from 1Hz to 5,000Hz. These frequencies correspond to the electrode at the test temperature of 600°C.

Triply-periodic nanostructures in surfactant, block copolymer, and biomembrane systems, and simulation of TEMs

1993 ◽  
Vol 51 ◽  
pp. 884-885
Author(s):  
David M. Anderson ◽  
Tomas Landh
Keyword(s):  
Liquid Crystalline ◽  
Diblock Copolymers ◽  
Cubic Phase ◽  
List Type ◽  
Interpenetrating Networks ◽  
Triply Periodic ◽  
Wide Range ◽  
Bicontinuous Cubic ◽  
Phase Liquid ◽  
Dividing Surface

First discovered in surfactant-water liquid crystalline systems, so-called ‘bicontinuous cubic phases’ have the property that hydropnilic and lipophilic microdomains form interpenetrating networks conforming to cubic lattices on the scale of nanometers. Later these same structures were found in star diblock copolymers, where the simultaneous continuity of elastomeric and glassy domains gives rise to unique physical properties. Today it is well-established that the symmetry and topology of such a morphology are accurately described by one of several triply-periodic minimal surfaces, and that the interface between hydrophilic and hydrophobic, or immiscible polymer, domains is described by a triply-periodic surface of constant, nonzero mean curvature. One example of such a dividing surface is shown in figure 5.The study of these structures has become of increasing importance in the past five years for two reasons:1)Bicontinuous cubic phase liquid crystals are now being polymerized to create microporous materials with monodispersed pores and readily functionalizable porewalls; figure 3 shows a TEM from a polymerized surfactant / methylmethacrylate / water cubic phase; and2)Compelling evidence has been found that these same morphologies describe biomembrane systems in a wide range of cells.

Ferroelectric Domain Structure of Pb(Zr.52Ti.48)03

1980 ◽  
Vol 38 ◽  
pp. 214-215
Author(s):  
E.K. Goo ◽  
R.K. Mishra
Keyword(s):  
Phase Transformation ◽  
Domain Structure ◽  
Tetragonal Phase ◽  
Ferroelectric Domain ◽  
Cubic Phase ◽  
Ion Milling ◽  
Thin Foils ◽  
Ferroelectric Domain Structure ◽  
Ferroelectric Domains

Ferroelectric domains are twins that are formed when PZT undergoes a phase transformation from a non-ferroelectric cubic phase to a ferroelectric tetragonal phase upon cooling below ∼375°C.,1 The tetragonal phase is spontaneously polarized in the direction of c-axis, making each twin a ferroelectric domain. Thin foils of polycrystalline Pb (Zr.52Ti.48)03 were made by ion milling and observed in the Philips EM301 with a double tilt stage.

EVALUATION OF THE EFFECT OF SPACER ON SUBCHANNEL MIXING IN ROD BUNDLES

2018 ◽  
Author(s):  
Arnab Dasgupta ◽  
Mitali Shah ◽  
Sudeep Metha ◽  
Vishnu Nair ◽  
Veeraj Sankalecha ◽  
...  
Keyword(s):  
Rod Bundles
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