Aggregation Behavior of a Symmetric, Fluorinated, Telechelic Polymer System Studied by19F NMR Relaxation

1999 ◽  
Vol 32 (8) ◽  
pp. 2690-2695 ◽  
Author(s):  
J. Preuschen ◽  
S. Menchen ◽  
M. A. Winnik ◽  
A. Heuer ◽  
H. W. Spiess
Keyword(s):  
Polymer System ◽  
Nmr Relaxation ◽  
Aggregation Behavior ◽  
Telechelic Polymer

Mononucleotides 31P NMR relaxation measurement

1983 ◽  
Vol 80 ◽  
pp. 831-832 ◽  
Author(s):  
A.M. Avedikian ◽  
D. Besserre ◽  
M. Delepierre
Keyword(s):  
31P Nmr ◽  
Nmr Relaxation ◽  
Relaxation Measurement

1H-NMR RELAXATION STUDIES ON THE NATURE OF THE SEMICONDUCTING STATE OF (TMTTF)2Br AND (TMTTF)2PF6: MAGNETISM

1983 ◽  
Vol 44 (C3) ◽  
pp. C3-1095-C3-1097
Author(s):  
T. Takahashi ◽  
F. Creuzet ◽  
D. Jérôme ◽  
J. M. Fabre
Keyword(s):  
1H Nmr ◽  
Nmr Relaxation ◽  
Relaxation Studies

Complex formation of modified chitosan and carboxymethyl cellulose and its effect on paper properties

TAPPI Journal ◽  
2009 ◽  
Vol 8 (6) ◽  
pp. 29-35 ◽  
Author(s):  
PEDRAM FATEHI ◽  
LIYING QIAN ◽  
RATTANA KITITERAKUN ◽  
THIRASAK RIRKSOMBOON ◽  
HUINING XIAO
Keyword(s):  
Carboxymethyl Cellulose ◽  
Polymer System ◽  
Layer By Layer ◽  
Paper Strength ◽  
Anionic Polymer ◽  
Paper Properties ◽  
Modified Chitosan ◽  
Layer By Layer Assembly ◽  
Polyelectrolyte Titration ◽  
Layer Assembly

The application of an oppositely charged dual polymer system is a promising approach to enhance paper strength. In this work, modified chitosan (MCN), a cationic polymer, and carboxymethyl cellulose (CMC), an anionic polymer, were used sequentially to improve paper strength. The adsorption of MCN on cellulose fibers was analyzed via polyelectrolyte titration. The formation of MCN/CMC complex in water and the deposition of this complex on silicon wafers were investigated by means of atomic force microscope and quasi-elastic light scattering techniques. The results showed that paper strength was enhanced slightly with a layer-by-layer assembly of the polymers. However, if the washing stage, which was required for layer-by-layer assembly, was eliminated, the MCN/CMC complex was deposited on fibers more efficiently, and the paper strength was improved more significantly. The significant improvement was attributed to the extra development of fiber bonding, confirmed further by scanning electron microscope observation of the bonding area of fibers treated with or without washing. However, the brightness of papers was somewhat decreased by the deposition of the complex on fibers. Higher paper strength also was achieved using rapid drying rather than air drying.

Structure and Dynamics of Spherical and Rodlike Alkyl Ethoxylate Surfactant Micelles Investigated Using NMR Relaxation and Atomistic Molecular Dynamics Simulations

2019 ◽  
Author(s):  
Allison Edwards ◽  
Abdolreza Javidialesaadi ◽  
Katie Weigandt ◽  
George Stan ◽  
Charles Eads
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Nmr Relaxation ◽  
Cross Relaxation ◽  
Relaxation Rates ◽  
Surfactant Micelles ◽  
Cylindrical Micelles ◽  
Spherical Micelles ◽  
Dynamics Simulations ◽  
Relative Motions

We study molecular arrangements and dynamics in alkyl ethoxylate nonionic surfactant micelles by combining high field (600 and 700 MHz) NMR relaxation measurements with large-scale atomistic molecular dynamics simulations. For spherical micelles, but not for cylindrical micelles, cross relaxation rates are positive only for surfactant alkyl tail atoms connected to the hydrophilic head group. All cross relaxation rates are negative for cylindrical micelles. This effect is reproducible either by changing composition (ratios of the nonionic surfactants) or changing temperature of a single surfactant in order to change the micelle shape. We validate the micelle shape by SANS and use the results as a guide for our simulations. We calculate parameters that determine relaxation rates directly from simulated trajectories, without introducing specific functional forms. Results indicate that relative motions of nearby atoms are liquid-like, in agreement with 13C T1 measurements, though constrained by micelle morphology. Relative motions of distant atoms have slower components because the relative changes in distances and angles are smaller when the moving atoms are further apart. The slow, long-range motions appear to be responsible for the predominantly negative cross relaxation rates observed in NOESY spectra. The densities of atoms from positions 1 and 2 in the boundary region are lower in spherical micelles compared to cylindrical micelles. Correspondingly, motions in this region are less constrained by micelle morphology in the spherical compared to the cylindrical cases. The two effects of morphology lead to the unusual occurrence of positive cross relaxation involving positions 1 and 2 for spheres.

Aggregation Behavior and Thermodynamic Studies of Hydrotropes: A Review

2020 ◽  
Vol 57 (3) ◽  
pp. 192-202 ◽  
Author(s):  
Akash D. Patel ◽  
Meghal A. Desai
Keyword(s):  
Aggregation Behavior ◽  
Thermodynamic Studies

MONOLAYERS LENGMYUR AZAKRAUN-ESSENTIAL DERIVATIVES OF CALIXES[4]ARENA

2018 ◽  
Vol 1 (11(56)) ◽  
pp. 62-64
Author(s):  
A.A. Muravev ◽  
E.A. Ivanova ◽  
A.T. Yakupov
Keyword(s):  
Aggregation Behavior ◽  
Langmuir Films ◽  
Azacrown Ether ◽  
Derivatives Of

In this work, aggregation behavior of azacrown-ether derivatives on a macrocyclic calix[4]arene scaffold within ultrathin Langmuir films on water subphase is considered.

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