Rigid-rod molecules

Figure 10.2 Single molecule force-extension curve of three different types of molecules (a) a short chain or rigid rod molecule (red) (b) a long chain polymer with multiple domains, such as titin (green), where bi-b represents the unfolding of individual domains and (c) a regular random coil long chain (blue). Adapted from Smith et al. (1999). Copyright 1999 Namre Publishing Group.

Wada 109, 110) pioneered studies of polypeptide conformation by the dielectric method. He found 110) a linear dependence of (ft2)1 2 on Mw for a series of PBLG samples (ranging from 7 x 104 to 18 x 104 in Mw) in EDC at 25° C and obtained 3.5 D for gh, where D stands for debye units. He computed (ft2) by the use of an approximate equation derived by himself 109) for rigid-rod molecules, which for very dilute solutions may be written... 

Sakai, N., Mareda, J., Matile, S., Rigid rod molecules in biomembrane models From hydrogen-bonded chains to synthetic... 

The Lorentz-Lorenz equation can be used directly to model the birefringence of a solution of rigid rod molecules subject to an orienting, external field. Figure 7.2 shows a representative molecule, which is modeled as having a uniaxial polarizability of the form... 

The molecular theory of Doi [63,166] has been successfully applied to the description of many nonlinear rheological phenomena in PLCs. This theory assumes an un-textured monodomain and describes the molecular scale orientation of rigid rod molecules subject to the combined influence of hydrodynamic and Brownian torques, along with a potential of interaction (a Maier-Saupe potential is used) to account for the tendency for nematic alignment of the molecules. This theory is able to predict shear thinning viscosity, as well as predictions of the Leslie viscosity coefficients used in the LE theory. The original calculations by Doi for this model employed a preaveraging approximation that was later... 

L Length scale of a light scattering volume, (6.10) length of a rigid rod molecule, Figure 7.6. 

Sakai, N., Brennan, K.C., Weiss, L.A. and Matile, S. (1997) Toward biomimetic ion channels formed by rigid-rod molecules Length-dependent ion-transport activity of substituted oligo-(p-phenylene)s. Journal of the American Chemical Society, 119, 8726-7. 

P2 J. Michl, Supramolecular Assemblies from Tinkertoy Rigid-Rod Molecules in Mesomolecules From Molecules to Materials, G. D. Mendenhall, A. Greenberg, J. F. Liebman, Chapman Hall, SEARCH Series, Vol. 1, Chapt. 5, 1995, pp. 132-160. 

Supramolecular Assemblies from Tinkertoy Rigid-Rod Molecules [J. Michl, Chapt. 5, pp. 132-160]. 

EQUILIBRIUM DRIVING FORCE FOR SEPARATIVE DISPLACEMENT RIGID-ROD MOLECULES SPHERICAL MOLECULES... 

K. M. Zero and R. Pecora, Rotational and translational diffusion in semi-dilute solutions of rigid-rod molecules. Macromolecules, 15 (1982) 87-93. 

HOYTETAL. Rigid Rod Molecules as Liquid-Crystalline Thermosets... 

PBZT and PBO are ordered polymers which form long rigid-rod molecules which give rise to a microfibrillar network structure in biaxially oriented films (Figure 1). Such biaxial films have been used in combination with low dielectric constant resins, such as cyanate ester resins, to make circuit substrates for use in MLBs... 

Notably, long rigid-rod molecules possessing two thiol groups on the rod termini are attached to the surface via only one thiol group, the other being at the monolayer-solution interface. By contrast, shorter molecules, such as 1,4-benzenedithiol, have both thiolate functions anchored to the Ag(lll) surface, and therefore adopt an orientation parallel to the surface31. 

Materials. On the basis of the observations made above, the choice of molecular design has centered on that of an extended chain, rigid-rod molecule for reasons of molecular ordering and an aromatic-heterocyclic structure for thermal and oxidative stability. Three such polymers have been synthesized, PDIAB,(5) PBO,(3,6,7) and PBT.(8)... 

Utracki and Lyngaae-Jprgensen [2002] observed several common aspects of exfoliated CPNCs and liquid-crystal polymers (LCPs). Similar six-phase structures are predicted for CPNCs and observed in LCPs isotropic, nematic, smectic-A, columnar, house of cards, and crystal [Porter and Johnson, 1967 Balazs et al., 1999 Ginzburg et al., 2000]. These phases in CPNCs originate in a balance between the thermodynamic interactions, clay concentration, and platelets orientation, while in LCPs they depend mainly on temperature. Since it is more difficult on the one hand to prepare disk-shaped than rigid-rod molecules, and on the other to develop flow theory for LCPs with disk moieties, the number of publications on the latter systems is small [Ciferri, 1991]. 

PROPERTIES OF SPECIAL INTEREST Hydrodynamic rigid-rod molecule, unusual chain stiffness, helical conformation. ... 

OTHER POLYMERS SHOWING THIS SPEOAL PROPERTY Rigid-rod molecule, helical conformation poly(n-hexyl isocyanate), poly(7-benzyl-L-glutamate). 

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