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Rod-like

A nematic liquid crystal cell, based on Merck Licrilite E202, was used in these experiments. The rod like liquid crystal molecules preferentially aligned themselves with each other and to an alignment surface in the liquid crystal device. Any birefringence. An, was given as the difference between the two orthogonal refractive indices. As a consequence, any resulting... [Pg.680]

Figure B3.6.4. Illustration of tliree structured phases in a mixture of amphiphile and water, (a) Lamellar phase the hydrophilic heads shield the hydrophobic tails from the water by fonning a bilayer. The amphiphilic heads of different bilayers face each other and are separated by a thin water layer, (b) Hexagonal phase tlie amphiphiles assemble into a rod-like structure where the tails are shielded in the interior from the water and the heads are on the outside. The rods arrange on a hexagonal lattice, (c) Cubic phase amphiphilic micelles with a hydrophobic centre order on a BCC lattice. Figure B3.6.4. Illustration of tliree structured phases in a mixture of amphiphile and water, (a) Lamellar phase the hydrophilic heads shield the hydrophobic tails from the water by fonning a bilayer. The amphiphilic heads of different bilayers face each other and are separated by a thin water layer, (b) Hexagonal phase tlie amphiphiles assemble into a rod-like structure where the tails are shielded in the interior from the water and the heads are on the outside. The rods arrange on a hexagonal lattice, (c) Cubic phase amphiphilic micelles with a hydrophobic centre order on a BCC lattice.
Altliough tire majority of studies on model colloids involve (quasi-) spherical particles, tliere is a growing interest in the properties of non-spherical colloids. These tend to be eitlier rod-like or plate-like. [Pg.2670]

One model for rod-like colloids is tire tobacco mosaic vims (TM V), which consists of rods of diameter D about 18 nm and lengtli L of 300 nm [17,18]. These colloids have tire advantage of being quite monodisperse, but are hard to obtain in large amounts. The fd vims gives longer, semi-flexible rods (L = 880 nm, D = 9 nm) [18,19]. Inorganic boehmite rods have also been prepared successfully [20]. [Pg.2670]

Otlier possibilities for observing phase transitions are offered by suspensions of non-spherical particles. Such systems can display liquid crystalline phases, in addition to tire isotropic liquid and crystalline phases (see also section C2.2). First, we consider rod-like particles (see [114, 115], and references tlierein). As shown by Onsager [116, 117], sufficiently elongated particles will display a nematic phase, in which tire particles have a tendency to align parallel to... [Pg.2689]

Wen X, Meyer R B and Caspar OLD 1989 Observation of smectic-A ordering in a solution of rigid-rod-like particles Rhys. Rev. Lett. 63 2760-3... [Pg.2690]

Rodium complexes Rod-like liquid crystals Rod nulls Roelen reaction Rohypnol Roica... [Pg.858]

The wide variety of ketomethylene and amino ketone monomers that could be synthesized, and the abiUty of the quinoline-forming reaction to generate high molar mass polymers under relatively mild conditions, allow the synthesis of a series of polyquinolines with a wide stmctural variety. Thus polyquinolines with a range of chain stiffness from a semirigid chain to rod-like macromolecules have been synthesized. Polyquinolines are most often prepared by solution polymerization of bis(i9-amino aryl ketone) and bis (ketomethylene) monomers, where R = H or C H, in y -cresol with di-y -cresyl phosphate at 135—140°C for a period of 24—48 h (92). [Pg.538]

Metallomesogens. It is also possible to synthesize compounds based on metal atoms which possess Hquid crystal phases. The series based on dithiolene complexes (1), where M = Ni, Pd, or Pt, contains a number of compounds which show the Hquid crystal phases typical of rod-like molecules (13,14). [Pg.196]

Disk-shaped molecules based on a metal atom possess discotic Hquid crystal phases. An example is octasubstituted metaHophthalocyanine. FiaaHy, metallomesogens which combine both rod-like and disk-like features iato a single molecule adopt the biaxial nematic phase. In addition to there being a preferred direction for orientation of the longest molecular axis as is tme for the nematic phase, perpendicular to this direction is another preferred direction for orientation of the shortest molecular axis (12). NonmetaHomesogens which combine both rod- and disk-like features iato a single molecule also adopt a biaxial nematic phase, but at least ia one case the amount of biaxiaHty is very small (15). [Pg.196]

Above the solution treatment temperature (ca 1250°C), the alloy is single phase with a bcc crystal stmcture. During cooling to ca 750—850°C, the sohd solution decomposes spinodally into two other bcc phases a and lattice parameter composition. The matrix a-phase is rich in Ni and Al and weakly magnetic as compared with which is rich in Fe and Co. The a -phase tends to be rod-like in the (100) dkection and ca 10 nm in diameter and ca 100 nm long. As the temperature is decreased, segregation of the elements becomes mote pronounced and the difference between the saturation polarizations of the two phases increases. [Pg.380]

Most polymeric Hquid crystals are based on stiff rod-like molecular units which are called calamitic mesogens. There are some unusual polymers (which are not discussed here) that contain flat disk-like molecular units called discotic mesogens in which the disks form columnar arrays like stacks of poker chips. [Pg.306]

Intractable, rigid, rod-like polyimides have been synthesized by way of polyisoimides (50). A large number of high molecular weight polyisoimides were also synthesized and characterized for the purpose of preparing semiinterpenetrating (SIPN) polyimide matrices and adhesives (51—53). [Pg.402]

Polymerization by G—G Goupling. An aromatic carbon—carbon coupling reaction has been employed for the synthesis of rigid rod-like polyimides from imide-containing dibromo compounds and aromatic diboronic acids ia the presence of palladium catalyst, Pd[P(CgH )2]4 (79,80). [Pg.403]

With appropriate caUbration the complex characteristic impedance at each resonance frequency can be calculated and related to the complex shear modulus, G, of the solution. Extrapolations to 2ero concentration yield the intrinsic storage and loss moduH [G ] and [G"], respectively, which are molecular properties. In the viscosity range of 0.5-50 mPa-s, the instmment provides valuable experimental data on dilute solutions of random coil (291), branched (292), and rod-like (293) polymers. The upper limit for shearing frequency for the MLR is 800 H2. High frequency (20 to 500 K H2) viscoelastic properties can be measured with another instmment, the high frequency torsional rod apparatus (HFTRA) (294). [Pg.201]

Baker, J. and Williams, A., Hypervelocity Penetration of Plate Targets by Rod and Rod-Like Projectiles, Internal. J. Impact Engrg. 5 (1-4), 101-110 (1987). [Pg.373]

The properties of an alloy (yield strength, toughness, oxidation resistance, etc.) depend critically on its constitution and on two further features of its structure the scale (nm or ym or mm) and shape (round, or rod-like, or plate-like) of the phases, not described by the constitution. The constitution, and the scale and shape of the phases, depend on the thermal treatment that the material has had. [Pg.324]

Figure 14.1 Each polypeptide chain in the collagen molecule folds into an extended polyproline type II helix with a rise per turn along the helix of 9.6 A comprising 3.3 residues. In the collagen molecule three such chains are supercoiled about a common axis to form a 3000-A-long rod-like molecule. The amino acid sequence contains repeats of -Gly-X-Y- where X is often proline and Y is often hydroxyproline. (a) Ball and stick model of two turns of one polypeptide chain. Figure 14.1 Each polypeptide chain in the collagen molecule folds into an extended polyproline type II helix with a rise per turn along the helix of 9.6 A comprising 3.3 residues. In the collagen molecule three such chains are supercoiled about a common axis to form a 3000-A-long rod-like molecule. The amino acid sequence contains repeats of -Gly-X-Y- where X is often proline and Y is often hydroxyproline. (a) Ball and stick model of two turns of one polypeptide chain.
The liquid crystal polymers consist of rod-like molecules which, during shear, tend to orient in the direction of shear. Because of the molecular order the molecules flow past each other with comparative ease and the melts have a low viscosity. When the melt is cooled the molecules retain their orientation, giving self-reinforcing materials that are extremely strong in the direction of orientation. [Pg.53]

The outstanding morphological feature of these rubbers arises from the natural tendency of two polymer species to separate one from another, even when they have similar solubility parameters. In this case, however, this is restrained because the blocks are covalently linked to each other. In a typical commercial triblock the styrene content is about 30% of the total, giving relative block sizes of 14 72 14. At this level the styrene end blocks tend to congregate into spherical or rod-like glassy domains embedded in an amorphous rubbery matrix. These domains have diameters of about 30 nm. [Pg.297]

In Chapter 3 it was pointed out that certain rod-like polymers showed many of the attributes of liquid crystals in the melt. In particular, these molecules were oriented in shear to such an extent that interchain entanglement was small and the melts had a low viscosity. On cooling of the melt these rod-like molecules remained oriented, effectively self-reinforcing the polymer in the direction of flow. The essential differences in the properties of liquid crystal polymers... [Pg.733]

FIG. 13 A colloidal liquid crystal. The rod-like particles point to a preferred diree-tion, called the nematic director. The solvent is disordered. [Pg.763]

BD. Dynamical correlations in suspensions of charged rod-like particles were simulated [121]. [Pg.766]


See other pages where Rod-like is mentioned: [Pg.681]    [Pg.2367]    [Pg.36]    [Pg.208]    [Pg.350]    [Pg.350]    [Pg.206]    [Pg.64]    [Pg.64]    [Pg.68]    [Pg.202]    [Pg.388]    [Pg.325]    [Pg.380]    [Pg.240]    [Pg.306]    [Pg.306]    [Pg.306]    [Pg.307]    [Pg.343]    [Pg.191]    [Pg.274]    [Pg.287]    [Pg.105]    [Pg.734]    [Pg.900]    [Pg.534]    [Pg.541]   
See also in sourсe #XX -- [ Pg.108 ]




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Electrolyte Solution Containing Rod-like Divalent Cations

Electrolyte Solution Containing Rod-like Zwitterions

Entanglement networks of rod-like micelles

Liquid crystals of rod-like molecules

Mesogens rod-like

Micelle rod-like

Molecules with Rod-Like Mesogens

Phase Transitions in Rod-Like Liquid Crystals

Phase Transitions in Suspensions of Rod-Like Colloids Plus Polymers

Rigid rod-like chain

Rigid rod-like polymers

Rigid rod-like structure

Rod like Polypeptides

Rod-Like Liquid Crystals Combining RH- and RF-Chains Monolayer Smectic Phases

Rod-Like Liquid Crystals with Fluorinated Chains

Rod-Like Liquid Crystals with Two Fluorinated Chains at Opposite Ends Layer Frustration

Rod-Like Structures with Longitudinal Density Modulation

Rod-like Colloids Plus Ideal Polymers

Rod-like Colloids Plus Interacting Polymers

Rod-like Molecules and Phenol Formaldehyde Oligomers

Rod-like colloids

Rod-like crystallites

Rod-like defects

Rod-like liquid crystals

Rod-like macromolecules

Rod-like mesogen

Rod-like mesogenic molecule

Rod-like micelles cationic surfactants

Rod-like micelles concentration

Rod-like micelles domain morphology

Rod-like micelles flexibility

Rod-like micelles rheology

Rod-like micelles shear behaviour

Rod-like molecule

Rod-like molecules as single substances

Rod-like morphology

Rod-like polymers

Rod-like polymers in concentrated solutions

Rod-like structure

Thermoreversible gelation of rigid rod-like and semirigid polymers

Thermotropic Mesophases Formed by Achiral Rod-Like Molecules

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