Diffusion and interaction in gels and solutions. 2. Experimental results on the obstruction effect

Johansson, Lennart; Skantze, Urban; Loefroth, Jan Erik

doi:10.1021/ma00022a018

Cited by 98 publications

(117 citation statements)

References 5 publications

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“…A similar results has been found by Johansson et al I-1, [37][38][39][40] in their self-diffusion study of C~2Es, PEG, glucose and sucrose in K÷-x-carrageenan gels and in Na+-x-carrageenan solutions at 25 °C. In contrast to C12Ea, D/Do for both C12E6 and PE6400 in agarose gels and solutions decreases at increasing temperature (see Figs.…”

Section: Resultssupporting

confidence: 88%

Mixtures of gelling agarose with nonionic surfactants or block-copolymers: Clouding and diffusion properties

Penders

Piculell

Lindman

et al.

Trends in Colloid and Interface Science VIII

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The clouding and diffusion behavior of nonionic micellar systems of dodecyl hexaoxyethylene (C12E6), dodecyl octaoxyethylene (C12Ea) glycol monoethers and a triblock copolymer of composition E13PO3oEO 13 (PE6400) have been investigated in agarose gels and solutions with and without sodium thiocyanate. In the presence of agarose the clouding temperature of the nonionic surfactant decreased on cooling and a hysteresis behavior was observed. However, the gelation temperature of agarose remained practically unchanged on the addition of surfactant; also, the diffusion of the surfactant was reduced due to obstruction caused by the polymer.

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Section: Resultssupporting

confidence: 88%

Mixtures of gelling agarose with nonionic surfactants or block-copolymers: Clouding and diffusion properties

Penders

Piculell

Lindman

et al.

Trends in Colloid and Interface Science VIII

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“…[44] to the experimental data. From the nonlinear regression analysis, the product K eq k ␤ was found to equal 10.3 s Ϫ1 (error ϭ 2.83%) for 5% C gels, and 2.98 s Ϫ1 (error ϭ 0.91%) for 10% C gels.…”

Section: Spin-lattice Relaxationmentioning

confidence: 99%

“…Figure 13 shows the effective relaxation rate constant, k eff T data, and the model (Eq. [44]) using K eq k ␤ values of 10.3 and 2.98 s Ϫ1 for 5 and 10% gels, respectively, as functions of the inverse volume fraction, (⑀ l ϩ ⑀ f ) Ϫ1 . The model, Eq.…”

Section: Spin-lattice Relaxationmentioning

confidence: 99%

“…Other approaches, including hindered transport theory (40,41), have also been used to describe the effects of solute size on diffusion. Experimental data typically has been interpreted on the basis of a stretched exponential equation (36,(42)(43)(44) which can be justified theoretically through comparison with Monte Carlo simulations or derived using a specific arrangement of a unit cell. Despite these studies, a full range of experimental measurements on probe diffusion in polyacrylamide gels as functions of gel composition, including crosslinker density, has not been reported; in addition, the effects of media geometry and solute-gel interactions have not been incorporated within one comprehensive approach.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Proton Diffusion andT1Relaxation in Polyacrylamide Gels: A Unified Approach Using Volume Averaging

Penke

Kinsey

Gibbs

et al. 1998

Journal of Magnetic Resonance

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The structure of polyacrylamide gels was studied using proton spin-lattice relaxation and PFG diffusion methods. Polyacrylamide gels, with total polymer concentrations ranging from 0.25 to 0.35 g/ml and crosslinker concentrations from 0 to 10% by weight, were studied. The data showed no effect of the crosslinker concentration on the diffusion of water molecules. The Ogston-Morris and Mackie-Meares models fit the general trends observed for water diffusion in gels. The diffusion coefficients from the volume averaging method also fit the data, and this theory was able to account for the effects of water-gel interactions that are not accounted for in the other two theories. The averaging theory also did not require the physically unrealistic assumption, required in the other two theories, that the acrylamide fibers are of similar size to water molecules. Contrary to the diffusion data, T 1 relaxation measurements showed a significant effect of crosslinker concentration on the relaxation of water in gels. The model developed using the Bloch equations and the volume averaging method described the effects of water adsorption on the gel medium on both the diffusion coefficients and the relaxation measurements. In the proposed model the gel medium was assumed to consist of three phases (i.e., bulk water, uncrosslinked acrylamide fibers, and a bisacrylamide crosslinker phase). The effects of the crosslinker concentration were accounted for by introducing the proton partition coefficient, K eq , between the bulk water and crosslinker phase. The derived relaxation equations were successful in fitting the experimental data. The partition coefficient, K eq , decreased significantly as the crosslinker concentration increased from 5 to 10% by weight. This trend is consistent with the idea that bisacrylamide tends to form hydrophobic regions with increasing crosslinker concentration.

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“…It has been shown, in the case of j-carrageenan gels, that the formation of a network by stiff molecules, instead of flexible molecules, induced a decrease of diffusion coefficients of probes. 34 In another words, the increase in flexibility enhanced the diffusion of the probe molecules. These results found also support in a theoretical study.…”

mentioning

confidence: 99%

PFG‐NMR diffusometry: A tool for investigating the structure and dynamics of noncommercial purified pig gastric mucin in a wide range of concentrations

et al. 2007

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For the first time, Pulsed Field Gradient-Nuclear Magnetic Resonance, a powerful noninvasive tool for studying the dynamics and structure of complex gels, has been used to measure diffusion of probe molecules in aqueous solutions/gels of noncommercial purified pig gastric mucin (PGM), in a concentration range up to 5 wt %. Complementary data were obtained from rheology measurements. The combination of techniques revealed a strong pH dependency of the structure of the PGM samples while changes in concentration, ionic strength, and temperature appeared to induce less pronounced alterations. Viscosity was found to vary in a nonmonotonous way with pH, with the more viscous solutions found at intermediate pH. We propose that this finding is due to a reduced charge density at lower pH, which is expected to continuously increase the relative importance of hydrophobic associations. The results suggest a loose network of expanded fully charged PGM molecules with considerable mobility at neutral pH (pH 7.4). At intermediate pH (pH 4), a three-dimensional expanded network is favored. At pH 1, the charge density is low and microphase separation occurs since hydrophobic associations prevail. This leads to the formation of clusters concentrated in PGM molecules separated by regions depleted in PGM. The results obtained increase our knowledge about the gastric mucosal layer, which in vivo contains mucin in the same concentration range as that of the samples investigated here.

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Diffusion and interaction in gels and solutions. 2. Experimental results on the obstruction effect

Cited by 98 publications

References 5 publications

Mixtures of gelling agarose with nonionic surfactants or block-copolymers: Clouding and diffusion properties

Mixtures of gelling agarose with nonionic surfactants or block-copolymers: Clouding and diffusion properties

Proton Diffusion andT1Relaxation in Polyacrylamide Gels: A Unified Approach Using Volume Averaging

PFG‐NMR diffusometry: A tool for investigating the structure and dynamics of noncommercial purified pig gastric mucin in a wide range of concentrations

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