Charge-regularized swelling kinetics of polyelectrolyte gels: Elasticity and diffusion

2017 ◽  
Vol 147 (17) ◽  
pp. 174901 ◽  
Author(s):  
Swati Sen ◽  
Arindam Kundagrami
Keyword(s):  
Swelling Kinetics ◽  
Polyelectrolyte Gels ◽  
Kinetics Of ◽  
And Diffusion

scholarly journals Polyelectrolyte Gels: A Unique Class of Soft Materials

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 102
Author(s):  
Ferenc Horkay
Keyword(s):  
Exchange Process ◽  
Interaction Strength ◽  
Soft Materials ◽  
Industrial Applications ◽  
Future Research ◽  
Swelling Kinetics ◽  
Polyelectrolyte Gels ◽  
Ion Exchange Process ◽  
Counter Ions ◽  
Kinetics Of

The objective of this article is to introduce the readers to the field of polyelectrolyte gels. These materials are common in living systems and have great importance in many biomedical and industrial applications. In the first part of this paper, we briefly review some characteristic properties of polymer gels with an emphasis on the unique features of this type of soft material. Unsolved problems and possible future research directions are highlighted. In the second part, we focus on the typical behavior of polyelectrolyte gels. Many biological materials (e.g., tissues) are charged (mainly anionic) polyelectrolyte gels. Examples are shown to illustrate the effect of counter-ions on the osmotic swelling behavior and the kinetics of the swelling of model polyelectrolyte gels. These systems exhibit a volume transition as the concentration of higher valence counter-ions is gradually increased in the equilibrium bath. A hierarchy is established in the interaction strength between the cations and charged polymer molecules according to the chemical group to which the ions belong. The swelling kinetics of sodium polyacrylate hydrogels is investigated in NaCl solutions and in solutions containing both NaCl and CaCl2. In the presence of higher valence counter-ions, the swelling/shrinking behavior of these gels is governed by the diffusion of free ions in the swollen network, the ion exchange process and the coexistence of swollen and collapsed states.

scholarly journals Kinetics of Polyelectrolyte Gels

2020 ◽  
Vol 87 (6) ◽  
Author(s):  
Haohui Zhang ◽  
Mohammad Dehghany ◽  
Yuhang Hu
Keyword(s):  
Chemical Potential ◽  
Polymer Networks ◽  
Potential Gradient ◽  
Stimuli Responsive ◽  
Cross Diffusion ◽  
Crosslinked Polymer ◽  
Polyelectrolyte Gels ◽  
Kinetics Of ◽  
Ionizable Groups ◽  
And Diffusion

Abstract Polyelectrolyte (PE) gels consist of crosslinked polymer networks that are grafted with ionizable groups and ionic solution. Many stimuli-responsive gels, including pH-responsive, electric-responsive, and light-responsive ones, are PE gels. Most soft biological components are also PE gels. Due to the increasing scientific interests and applications of PE gels, a comprehensive model is needed. In PE gels, not only solvent, but also ions and other small molecules all diffuse inside, and the flows of the different components are coupled. This phenomenon is called cross-diffusion, meaning the flow of one species is not only driven by its own chemical potential gradient, but also influenced by the flow of other species. In this work, we develop a rigorous nonequilibrium thermodynamics framework to study the coupled deformation and diffusion of the PE gels where cross-diffusion is emphasized and quantified. Specific forms of free energy and kinetic laws are proposed. A finite element method is developed and implemented into abaqus through a user element subroutine. The model is used to simulate the deformation of biological axon and PE gels.The numerical results are compared with experimental data. It is shown that cross-diffusion generates anomalous effects not only on the flux but also on the deformation of PE gels.

scholarly journals Buffer effects on aqueous swelling kinetics of polyelectrolyte gels

1992 ◽  
Vol 45 (8) ◽  
pp. 1411-1423 ◽  
Author(s):  
Loretta Y. Chou ◽  
Harvey W. Blanch ◽  
John M. Prausnitz ◽  
Ronald A. Siegel
Keyword(s):  
Swelling Kinetics ◽  
Polyelectrolyte Gels ◽  
Kinetics Of ◽  
Buffer Effects

scholarly journals Biosorption and Diffusion Modeling of Pb(II) by Malt Bagasse

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Klaiani B. Fontana ◽  
Giane Gonçalves Lenzi ◽  
Erica R. L. R. Watanabe ◽  
Ervin Kaminski Lenzi ◽  
Juliana A. M. T. Pietrobelli ◽  
...  
Keyword(s):  
Sorption Process ◽  
Isotherm Models ◽  
Diffusion Modeling ◽  
Biosorption Capacity ◽  
Kinetic And Thermodynamic Parameters ◽  
Pseudo Second Order ◽  
Ph Optimization ◽  
Kinetics Of ◽  
And Diffusion

The removal of Pb(II) from water by biosorption processes onto malt bagasse was investigated and the kinetic and thermodynamic parameters were obtained; additionally a diffusion modeling was proposed. The characterization of malt bagasse was performed by FTIR and SEM/EDS. The experiments were conducted in batch system and an experimental design based response surface methodology was applied for agitation speed and pH optimization. The kinetics of biosorption followed pseudo-second-order model and the temperature of the process affected the biosorption capacity. Isotherm models of Langmuir, Freundlich, and Elovich were applied and the Langmuir model showed better fit and the estimated biosorption capacity was 29.1 mg g−1. The negative values obtained for ΔG° and positive values of ΔH° confirm, respectively, the spontaneous and endothermic nature of the process. The diffusion modeling was performed based on experiments in the absence of agitation to investigate the influence of the biosorbent on the sorption process of Pb(II) ions.

Vacancy-Mediated Diffusion and Diffusion-Controlled Processes in Ordered Binary Intermetallics by Kinetic Monte Carlo Simulations

2021 ◽  
Vol 29 ◽  
pp. 95-115
Author(s):  
Rafal Kozubski ◽  
Graeme E. Murch ◽  
Irina V. Belova
Keyword(s):  
Monte Carlo ◽  
Kinetic Monte Carlo ◽  
Simulation Studies ◽  
Self Diffusion ◽  
Monte Carlo Techniques ◽  
Diffusion Controlled ◽  
Kinetic Monte Carlo Simulations ◽  
Kinetic Effects ◽  
Kinetics Of ◽  
And Diffusion

We review the results of our Monte Carlo simulation studies carried out within the past two decades in the area of atomic-migration-controlled phenomena in intermetallic compounds. The review aims at showing the high potential of Monte Carlo methods in modelling both the equilibrium states of the systems and the kinetics of the running processes. We focus on three particular problems: (i) the atomistic origin of the complexity of the ‘order-order’ relaxations in γ’-Ni3Al; (ii) surface-induced ordering phenomena in γ-FePt and (iii) ‘order—order’ kinetics and self-diffusion in the ‘triple-defect’ β-NiAl. The latter investigation demonstrated how diverse Monte Carlo techniques may be used to model the phenomena where equilibrium thermodynamics interplays and competes with kinetic effects.

Kinetic model for disposition of 6-mercaptopurine in monkey plasma and cerebrospinal fluid

1985 ◽  
Vol 248 (2) ◽  
pp. R147-R156 ◽  
Author(s):  
D. G. Covell ◽  
P. K. Narang ◽  
D. G. Poplack
Keyword(s):  
Cerebrospinal Fluid ◽  
Brain Parenchyma ◽  
Lymphocytic Leukemia ◽  
Bolus Administration ◽  
Significant Barrier ◽  
Maintenance Of Remission ◽  
Kinetics Of ◽  
And Diffusion ◽  
Monkey Plasma ◽  
Csf Turnover

The antipurine 6-mercaptopurine (6-MP) is effective in the induction and maintenance of remission in patients with acute lymphocytic leukemia. This report presents a compartmental model that describes the kinetics of 6-MP in the plasma and cerebrospinal fluid (CSF) of the monkey. Analysis is based on simultaneously measured plasma and CSF 6-MP concentrations after intravenous and intraventricular bolus administration. Results indicate that 6-MP administered intraventricularly remains largely in the CSF. Disappearance of 6-MP from CSF is principally due to convective losses at a rate equivalent to CSF turnover. Diffusion of 6-MP across the ependymal surface accounts for only 7% of the 6-MP appearing in the plasma. Conversely the dominant route for entry of 6-MP into the CSF from the plasma is entrainment in choroidally formed CSF. Only 12% of 6-MP in the CSF after intravenous administration can be accounted for by permeation of cerebral capillaries and diffusion through brain parenchyma and across the ependymal surface into CSF. These results indicate that the choroid plexus is not a significant barrier for the transfer of molecules like 6-MP from plasma to CSF.

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