Diffusion and reactions of multicomponent electrolytes in poly(vinyl alcohol) hydrogels — modeling and experiment

Fergg, Florian; Keil, Frerich J.

doi:10.1016/s0009-2509(00)00353-5

Cited by 15 publications

(9 citation statements)

References 19 publications

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“…As for the morphological features of the continuous gel phase proper, its own porosity, as can be better seen in micrographs of Figure 9, is typical for PVA cryogels in general 3–5, 7–11, 31, 42, 58–62. The pores in these cryogels are usually long and anisotropic, with the cross‐section of the order of 1–2 μm,7, 8 Such key feature of PVA cryogels is the ground for their excellent diffusional properties.…”

Section: Resultsmentioning

confidence: 92%

“…The morphology of vof-PVACGs was studied using light microscopy. This technique was shown earlier [5][6][7][8][21][22][23][24][25][26]42,[58][59][60][61][62] to be informative regarding the macroporous structure of PVA cryogels, both the filled and the usual nonfilled ones, and the character of the filler particles distribution within the continuous phase of respective composites. Micrographs in Figures 8 and 9 exemplify the images of thin sections of vof-PVACGs prepared from the emulsions, whose pictures are given in Figure 3.…”

Section: Morphological Features Of Composite Pva Cryogels Filled Withmentioning

confidence: 99%

“…66 As for the morphological features of the continuous gel phase proper, its own porosity, as can be better seen in micrographs of Figure 9, is typical for PVA cryogels in general. [3][4][5][7][8][9][10][11]31,42,[58][59][60][61][62] The pores in these cryogels are usually long and anisotropic, with the cross-section of the order of 1-2 lm, 7,8 Such key feature of PVA cryogels is the ground for their excellent diffusional properties. This makes possible practical application of the usual nonfilled, as well as complex and composite PVACGs as, e.g., carriers of immobilized enzymes and cells, macroporous supports of immunosorbents, drug delivery matrices, etc.…”

Section: Morphological Features Of Composite Pva Cryogels Filled Withmentioning

confidence: 99%

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Cryostructuring of polymer systems. XXX. Poly(vinyl alcohol)‐based composite cryogels filled with small disperse oil droplets: A gel system capable of mechanically induced releasing of the lipophilic constituents

Podorozhko

Korlyukov

Lozinsky

2010

J of Applied Polymer Sci

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Composite heterophase poly(vinyl alcohol) (PVA) cryogels containing entrapped small droplets of Vaseline oil have been prepared and studied. Such oilfilled cryogels were formed via freeze-thaw treatment of freshly prepared oil-in-water emulsions containing varied volume fraction of lipophilic phase, and the influence of the amount of this phase, as well as the effects of freezing conditions on the physicomechanical (shear moduli) and thermal (gel fusion temperature and fusion enthalpy) characteristics of resulting composites have been explored. It was shown that over certain range of PVA concentrations in aqueous phase and a range of volume fraction of the hydrophobic phase its microdroplets performed as ''active'' fillers causing an increase in both the gel strength and the heat endurance of composites. The light microscopy data on the morphological features of such filled PVA cryogels revealed the effect of diminution in size of oil droplets entrapped in the gel matrix as compared with the initial emulsions. This effect can be explained by the disintegrating action of crushing and shear stresses arising upon the system freezing and growth of ice crystals. The oil-filled PVA cryogels were found to be capable of gradually releasing the lipophilic constituents (the Rose hips oil, in this case) in response to the cyclic mechanical compression.

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Section: Resultsmentioning

confidence: 92%

Section: Morphological Features Of Composite Pva Cryogels Filled Withmentioning

confidence: 99%

Section: Morphological Features Of Composite Pva Cryogels Filled Withmentioning

confidence: 99%

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Cryostructuring of polymer systems. XXX. Poly(vinyl alcohol)‐based composite cryogels filled with small disperse oil droplets: A gel system capable of mechanically induced releasing of the lipophilic constituents

Podorozhko

Korlyukov

Lozinsky

2010

J of Applied Polymer Sci

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“…34 The molecular dynamics and Monte Carlo approaches are also used to investigate the properties of hydrogels. [35][36][37][38][39][40][41] In addition, the macroscopic continuum theories are presented by coupling the chemical, electrical and mechanical effects together for analysis of the equilibrium or kinetics of the hydrogel. [42][43][44][45] More theoretical works have been reviewed on the modeling and simulation of smart hydrogel.…”

Section: Introductionmentioning

confidence: 99%

Modeling of effect of initial fixed charge density on smart hydrogel response to ionic strength of environmental solution

Lai

2010

Soft Matter

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A chemo-electro-mechanical model is presented for analysis of the influence of the initial fixed charge density on performance of ionic-strength-sensitive hydrogel, termed the multi-effect-coupling ionic-strength-stimulus (MECis) model. It is composed of Nernst-Planck convection-diffusion equations which describe the chemical field, Poisson equation which provides the electrical potential associated with the fixed charge equation based on the Langmiur adsorption theory, and the mechanical equation which demonstrates the deformable behavior of the polymeric network of the ionic-strength-sensitive hydrogel. In the MECis model, the ionic strength of the bathing solution is considered as a key stimulus and incorporated into the Nernst-Planck equations and fixed charge formulation via activity coefficient and apparent dissociation constant, which influence the convectiondiffusion characteristics and binding reaction. The initial fixed charge density is taken as an important chemical parameter for the indication of the amount of the ionizable monomer groups within the ionic-strength-sensitive hydrogel, since it reflects the swelling ability of the hydrogel. The initial fixed charge density also influences the binding ability of the mobile ions to the polymeric network that determines the driving force for the swelling, which is reflected by the fixed charge equation in the MECis model. The present simulation results are compared with the experiments for examination of the MECis model, and it is concluded that the MECis model can predict well the influence of the initial fixed charge density on the swelling behavior quantitatively and provide a good simulation platform for designing and optimization of the hydrogel-based BioMEMS. The parameter study is then conducted for analysis of the influence of the initial fixed charge density on the responsive characteristics of the ionic-strength-sensitive hydrogel including the ionic transport, electrical potential, and displacement.

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“…Khan and Chan (2003a) investigated the force extension behavior of charged polymers by MC simulation of strain and stress ensembles. Other MC approaches can also be found (Fergg and J. Keil, 2001; Khan and Chan, 2003b;Milchev et al, 1999;Schneider and Linse, 2003;Zifferer et al, 2002).…”

Section: Monte Carlo Simulationmentioning

confidence: 99%

Model development of ionic-strength-sensitive hydrogel and finite element analysis of gel and dielectrics

Lai¹

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V quantitatively. Further, the steady-state MECis model is also compared with the modified Flory-Rehner theory-I and-II, as well as the gel-swelling model. It is demonstrated that the present MECis model can work more accurately by considering more physical and chemical environmental conditions. In addition, the four parameter studies are carried out, in order to understand how the physical and chemical parameters affect the equilibrium characteristics of the ionic-strength-sensitive hydrogel, including the influences of the initial fixed charge density, the equilibrium constant, the Young's modulus, and the initial fixed charge distance on the equilibrium characteristics. The influence of these parameters is presented in terms of the swelling ratio, the chemical, electric and mechanical fields, where the distributions of several important field variables are analyzed in details, such as the fixed charge density, the ionic concentration, the electric potential, and the displacement. Apart from that, the kinetics of the ionic-strength-sensitive hydrogel is also analyzed by the transient MECis simulation, where the present model is employed first to investigate the kinetics of the swelling/shrinking and/or reversible properties of various ionic-strength-sensitive hydrogels, and then compared with the corresponding experiments. The comparisons show that the MECis model is capable of modeling and simulating of the kinetic characteristics of the ionic-strength-sensitive hydrogels accurately. The influence of the chemical and physical parameters is then studied systematically on the kinetic swelling/shrinking of the ionic-strength-sensitive hydrogel, where the reversible kinetics and the influences of the initial fixed charge density and Young's modulus on the kinetics of the hydrogel are discussed in details. The kinetics of the swelling ratio with different parameters, and the kinetic distributions of the significant field variables are analyzed as well, including the fixed charge density, the ionic concentration, the electric potential, and the displacement. Finally, the finite element methods are implemented for the investigation of the kinetic deformation of the gels in water and the equilibrium of dielectrics, respectively. Firstly, the kinetic deformation patterns of the gels with various shapes and constraints in water are analyzed by the finite element model, including the constrained, the block, the thin film, and the bonded gels, where different deformation patterns are achieved, such as the buckling, twisting, wrinkling, folding, and waving. The experiments are also carried out to observe the swelling and wrinkling of the cubic and thin film gels. The simulation is compared with the experiments and a good agreement is observed.

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Diffusion and reactions of multicomponent electrolytes in poly(vinyl alcohol) hydrogels — modeling and experiment

Cited by 15 publications

References 19 publications

Cryostructuring of polymer systems. XXX. Poly(vinyl alcohol)‐based composite cryogels filled with small disperse oil droplets: A gel system capable of mechanically induced releasing of the lipophilic constituents

Cryostructuring of polymer systems. XXX. Poly(vinyl alcohol)‐based composite cryogels filled with small disperse oil droplets: A gel system capable of mechanically induced releasing of the lipophilic constituents

Modeling of effect of initial fixed charge density on smart hydrogel response to ionic strength of environmental solution

Model development of ionic-strength-sensitive hydrogel and finite element analysis of gel and dielectrics

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