129Xe NMR in Polymers

1993 ◽  
Vol 66 (3) ◽  
pp. 455-461 ◽  
Author(s):  
J. B. Miller
Keyword(s):  
Chemical Shift ◽  
Amorphous Phase ◽  
Van Der Waals ◽  
Phase Morphology ◽  
Van Der Waals Interaction ◽  
Interaction Energies ◽  
Near Surface ◽  
129Xe Nmr ◽  
Spin Polarized ◽  
Bulk Polymers

Abstract Through the efforts of many researchers, 129Xe NMR has shown to be a sensitive probe of phase morphology in polymers, providing a unique means of investigating the amorphous phase of bulk polymers. Recently developed models of the 129Xe chemical shift in polymers open the possibility of measuring van der Waals' interaction energies and chain dimensions from xenon spectra. In most cases, the information obtained from 129Xe NMR pertains only to the amorphous phase of the polymer, even in semicrystalline systems. The use of spin-polarized xenon has opened the possibility of probing the surface and near surface regions of polymers.

scholarly journals Van der Waals interactions between polymers with sequence-specific polarizabilities: Stiff polymers and Gaussian coils

2016 ◽  
Vol 31 (02n03) ◽  
pp. 1641035 ◽  
Author(s):  
Bing-Sui Lu ◽  
Ali Naji ◽  
Rudolf Podgornik
Keyword(s):  
Interaction Energy ◽  
Van Der Waals ◽  
Pairwise Interaction ◽  
Van Der Waals Interaction ◽  
Van Der Waals Interactions ◽  
Attractive Interaction ◽  
Gyration Radius ◽  
Interaction Energies ◽  
Anisotropic Interaction ◽  
Decay Behavior

We consider the van der Waals interaction between a pair of polymers with quenched heterogeneous sequences of local polarizabilities along their backbones, and study the effective pairwise interaction energy for both stiff polymers and flexible Gaussian coils. In particular, we focus on the cases where the pair of polarizability sequences are (i) distinct and (ii) identical. We find that the pairwise interaction energies of distinct and identical Gaussian coils are both isotropic and exhibit the same decay behavior for separations larger than their gyration radius, in contradistinction to the orientationally anisotropic interaction energies of distinct and identical stiff polymers. For both Gaussian coils and stiff polymers, the attractive interaction between identical polymers is enhanced if the polarizability sequence is more heterogeneous.

LIQUID CRYSTAL MODELING: ELECTROSTATIC AND VAN DER WAALS INTERACTION ENERGIES FOR MOLECULAR BUILDING BLOCKS FROM BENZENE TO CHOLESTEROL

1999 ◽  
Vol 10 (02n03) ◽  
pp. 455-468
Author(s):  
BELINDA BRAUN ◽  
MANFRED HOHLA ◽  
JUTTA KÖHLER
Keyword(s):  
Liquid Crystal ◽  
Force Field ◽  
Intermolecular Interaction ◽  
Van Der Waals ◽  
Building Blocks ◽  
Glycyrrhetinic Acid ◽  
Van Der Waals Interaction ◽  
Interaction Energies ◽  
Molecular Building Blocks ◽  
Empirical Force Field

Intermolecular interaction energies for molecular dimers of benzene, indene, naphthalene, phenanthrene, cholesterol and glycyrrhetinic acid have been calculated according to the CVFF empirical force field of the DISCOVER program. The parallel orientations (side by-side) turned out to be the energetically most favourable ones, in agreement with the parametrization of Gay–Berne potentials. The energies of the T-shape and in-plane (end-to-end) orientations of the entirely asymmetric molecules cholesterol and glycyrrhetinic acid depend strongly on the actual atomic positions. This shows the extent to which the shape and charges of molecules determine all possible orientations and interaction energies in molecular ensembles.

Colloidal Interactions for Nanopatterned Surfaces Based on Surface Element Integration (SEI) Approach

2010 ◽  
Author(s):  
Amir Ehsan Hosseini ◽  
Subir Bhattacharjee ◽  
Eric M. V. Hoek
Keyword(s):  
Rough Surface ◽  
Electrostatic Interaction ◽  
Integration Method ◽  
Unit Area ◽  
Van Der Waals ◽  
Van Der Waals Interaction ◽  
Square Lattice ◽  
Surface Element ◽  
Interaction Energies ◽  
Colloidal Interactions

In this study, van der Waals and electrostatic interaction energies on a nanopatterned rough surface was investigated. Surface element integration method (SEI) was applied to determine the interaction between a nanostructured substrate and an infinite flat plate. Hemispherical protrusions or depressions were mathematically generated on a square lattice to represent the rough surface. The size of the asperities and the pitch (separation) between their centers were varied. From the above calculations, we have analyzed the coupling between the range of the interactions and the roughness features of the substrate by comparing the ratios of the rough surface to smooth surface interaction energies per unit area. At small separations, the rough surface van der Waals interaction is seriously attenuated in the presence of protruding asperities. This attenuation is less pronounced for depressions. The attenuation of the van der Waals interaction due to asperities diminishes at large separations. In contrast, attenuation of the electrostatic interaction is independent of the separation.

Calculations of van der Waals interaction energies for Al, Cr, Fe, and Ir acetylacetonate crystals

2006 ◽  
Vol 47 (6) ◽  
pp. 1032-1041 ◽  
Author(s):  
O. V. Prokuda ◽  
V. R. Belosludov ◽  
I. K. Igumenov ◽  
P. A. Stabnikov
Keyword(s):  
Van Der Waals ◽  
Van Der Waals Interaction ◽  
Interaction Energies
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