scholarly journals Temporal Changes of Adsorbed Layer Thickness and Electrophoresis of Polystyrene Sulfate Latex Particles after Long Incubation of Oppositely Charged Polyelectrolytes with Different Charge Densities

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2394
Author(s):  
Thi Hai Yen Doan ◽  
Tien Duc Pham ◽  
Johan Hunziker ◽  
Thu Ha Hoang
Keyword(s):  
Charge Density ◽  
Layer Thickness ◽  
Electrophoretic Mobility ◽  
Incubation Time ◽  
Adsorbed Layer ◽  
Charge Densities ◽  
Molecular Weights ◽  
Desorption Equilibrium ◽  
Adsorption Desorption ◽  
Oppositely Charged

The different desorption concepts of the two polyelectrolytes PTMA5M and PTMC5M, which have similar molecular weights and differ in the charge density on the polystyrene sulfate latex (PSL) particles by 25 times, and with various charge densities in a long incubation, were systematically investigated based on hydrodynamic adsorbed layer thickness (δH) and electrophoretic mobility (EPM) under two ionic strengths in the present study. Herein, in the case of highly charged polyelectrolyte PTMA5M, desorption continued for 4 h and re-adsorbing proceeded after a longer incubation time higher than 4 h. Meanwhile, in the case of lowly charged polyelectrolyte PTMC5M, an adsorption–desorption equilibrium was suggested to take into account the unchanging of both δH and EPM.

scholarly journals Separation and Characterization of Highly Charged Polyelectrolytes Using Free-Solution Capillary Electrophoresis

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1331
Author(s):  
Isabelle Desvignes ◽  
Joseph Chamieh ◽  
Hervé Cottet
Keyword(s):  
Capillary Electrophoresis ◽  
Ionic Strength ◽  
Charge Density ◽  
Electrophoretic Mobility ◽  
Separation Mechanism ◽  
Free Solution ◽  
Counterion Condensation ◽  
Charge Densities ◽  
Effective Mobility

The characterization of statistical copolymers of various charge densities remains an important and challenging analytical issue. Indeed, the polyelectrolyte (PE) effective electrophoretic mobility tends to level off above a certain charge density, due to the occurrence of Manning counterion condensation. Surprisingly, we demonstrate in this work that it is possible to get highly resolutive separations of charged PE using free-solution capillary electrophoresis, even above the critical value predicted by the Manning counterion condensation theory. Full separation of nine statistical poly(acrylamide-co-2-acrylamido-2-methylpropanesulfonate) polymers of different charge densities varying between 3% and 100% was obtained by adjusting the ionic strength of the background electrolyte (BGE) in counter electroosmotic mode. Distributions of the chemical charge density could be obtained for the nine PE samples, showing a strong asymmetry of the distribution for the highest-charged PE. This asymmetry can be explained by the different reactivity ratios during the copolymerization. To shed more light on the separation mechanism, effective and apparent selectivities were determined by a systematic study and modeling of the electrophoretic mobility dependence according to the ionic strength. It is demonstrated that the increase in resolution with increasing BGE ionic strength is not only due to a closer matching of the electroosmotic flow magnitude with the PE electrophoretic effective mobility, but also to an increase of the dependence of the PE effective mobility according to the charge density.

Glass Transition in Carbon Black Reinforced Rubber

1968 ◽  
Vol 41 (5) ◽  
pp. 1194-1202 ◽  
Author(s):  
P. P. A. Smit
Keyword(s):  
Glass Transition ◽  
Activated Carbon ◽  
Carbon Black ◽  
Layer Thickness ◽  
Dynamic Properties ◽  
Physical Adsorption ◽  
Adsorbed Layer ◽  
Simple Liquids ◽  
Black Surface ◽  
Adsorption Desorption

Abstract It can be stated that the effect of carbon black in a rubber vulcanizate with regard to dynamic properties can be explained by assuming physical adsorption of rubber on the black surface. The effect can be represented by assuming an adsorbed layer having different properties from the bulk rubber taking the layer thickness to be at least 20 A. Adsorption-desorption from this layer causes non-linearity and may contribute to losses observed in the glass transition. This adsorption is analogous to adsorption of simple liquids in microporous systems such as silica gel and activated carbon.

Charge density studies on methylene blue – a potential anti-Alzheimer agent

2018 ◽  
Vol 73 (2) ◽  
pp. 99-108 ◽  
Author(s):  
Peter Luger ◽  
Birger Dittrich ◽  
Leonard Benecke ◽  
Hannes Sterzel
Keyword(s):  
Methylene Blue ◽  
Charge Density ◽  
Molecular Electrostatic Potential ◽  
Positive Charge ◽  
Atomic Charges ◽  
Charge Densities ◽  
Density Distributions ◽  
Atomic Properties ◽  
Counter Ions ◽  
Medical Interest

AbstractMotivated by the medical interest in methylene blue as potential anti-Alzheimer agent, the charge densities of three salt structures containing the methylene blue cation with nitrate (as dihydrate), chloride (as pentahydrate) and thiocyanate counter-ions were generated by application of the invariom formalism and examined. The so-obtained charge density distributions were analyzed using the QTAIM formalism to yield bond topological and atomic properties. The atomic charges on the methylene blue cation indicate a delocalized charge distribution; only a small positive charge on the sulfur atom was found. Electrostatic potentials mapped onto iso-surfaces of electron density for the cations, and for the methylene blue cations with anions, were compared. The effect of hydrogen disorder on the molecular electrostatic potential was investigated for the thiocyanate structure.

Heterogeneous Interactions of Methylamines on porous Adsorbents Part II. Interactions on Silica–Alumina and Silica Gel Surfaces of Di- and Tri-methylamine in the Region of their Boiling Points

1972 ◽  
Vol 50 (15) ◽  
pp. 2451-2456 ◽  
Author(s):  
W. G. Cook ◽  
R. A. Ross
Keyword(s):  
Silica Gel ◽  
Surface Coverage ◽  
Adsorbed Layer ◽  
Silica Gels ◽  
Heats Of Adsorption ◽  
Boiling Points ◽  
Silica Alumina ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
Heterogeneous Interactions

The adsorption of di- and tri-methylamine has been studied at 280 and 276°K, respectively, on a range of silica gels and on silica–alumina. Adsorption–desorption isotherms and isothermal calorimetric heats of adsorption were measured. Heats of adsorption for di-methylamine on silica gel varied from 29.0 kcal/mol at θ = 0.05 to 12.0 kcal/mol at monolayer completion, while for silica–alumina the heats fell from 31.4 to 9.0 kcal/mol between these same values of surface coverage. For tri-methylamine on silica gel, heats fell from 21.0, θ = 0.05, to 10.3 kcal/mol, θ = 1.00, while heats of 21.4 and 9.9 kcal/mol, respectively, were found at these same surface coverages on silica–alumina. The values of the heats of adsorption are discussed in terms of interactions in the adsorbed layer which are believed to be influenced by the pore sizes in the adsorbent and by the basicity of the amine molecules.

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