Pulsed field gradient NMR study of probe motion in polyacrylamide gels

Gibbs, S. Julian; Johnson, Charles S.

doi:10.1021/ma00023a010

Cited by 33 publications

(19 citation statements)

References 8 publications

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“…With the exception of PEG-10,000 (␣ ϭ 10.95), the parameter ␣ seems to remain quite constant. A linear dependence between ␣ and R h was suggested by Russo et al, 41 but Park et al, 42 and Gibbs and Johnson 43 reported ␣ being equal to 3.03 R h 0.59 and 3.2 R h 0.53 , respectively, which is not observed in this study. The parameter is found also to be more or less constant with an average value of 0.74 for these diffusants (Table I).…”

Section: 40 (3) the Hydrodynamic Modelscontrasting

confidence: 70%

Study of the self-diffusion of poly(ethylene glycol)s in poly(vinyl alcohol) aqueous systems

Masaro

Zhu

Macdonald

1999

J. Polym. Sci. B Polym. Phys.

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Section: 40 (3) the Hydrodynamic Modelscontrasting

confidence: 70%

Study of the self-diffusion of poly(ethylene glycol)s in poly(vinyl alcohol) aqueous systems

Masaro

Zhu

Macdonald

1999

J. Polym. Sci. B Polym. Phys.

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“…In the present study, the fitting parameters n 1 and n 2 were 5.32 and 0.76, respectively. However, the scaling parameter n 1 was predicted to depend strongly on the hydrodynamic radius (Gibbs and Johnson, 1991). Additionally, the diffusion coefficient in the PVA gel beads was lower than D aq (3.765 × 10 −10 m 2 /s) in the pure water because of the exclusion ef- fect, obstruction effect, and hydrodynamic drag effect (Muhr and Blanshard, 1982;Westrin and Axelsson, 1991).…”

Section: Characteristics Of Azo Dye Diffusion In Pva Gel Beadsmentioning

confidence: 96%

Evaluation of effective diffusion coefficient and intrinsic kinetic parameters on azo dye biodegradation using PVA‐immobilized cell beads

Chen

Yang

et al. 2003

Biotech & Bioengineering

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An immobilized mixed culture (Aeromonas hydrophila, Comamonas testosteroni, and Acinetobacter baumannii) was prepared by entrapment into phosphorylated polyvinyl alcohol (PVA) gel beads. The unsteady-state diffusion mechanism in a gel bead was applied to estimate the effective diffusion coefficients (D(e)) and the partition coefficients (K(p)) of azo dye. In addition, a simple method was developed to determine the intrinsic kinetic parameters of immobilized cells from observed reaction rates and the intrinsic kinetic parameters were then verified by fitting the experimental data into the reaction-diffusion model in a batch reactor running at a well-stirred state. The calculated effectiveness factor (eta(cal)) approached unity at Thiele modulus (Phi) < 0.3 (i.e., d(p) < 0.475 mm). The experimental effectiveness factor (eta(exp)) was in the range of 0.71-0.45 for a corresponding sphere diameter (d(p)) of 1.91 +/- 0.16 to 4.43 +/- 0.07 mm at an initial dye concentration of 200 mg/L. The results show that intraparticle diffusion resistance has a significant effect on the azo dye biodegradation rate.

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“…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%

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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Pulsed field gradient NMR study of probe motion in polyacrylamide gels

Cited by 33 publications

References 8 publications

Study of the self-diffusion of poly(ethylene glycol)s in poly(vinyl alcohol) aqueous systems

Study of the self-diffusion of poly(ethylene glycol)s in poly(vinyl alcohol) aqueous systems

Evaluation of effective diffusion coefficient and intrinsic kinetic parameters on azo dye biodegradation using PVA‐immobilized cell beads

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

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