Concentration Dependence of Mechanical Properties of Polyacrylamide near the Sol-Gel Transition Point

Yano, Toshimasa; Kumagai, Hitoshi; Fujii, Tomoyuki; Inukai, Tetsuo

doi:10.1271/bbb.57.528

Cited by 14 publications

(5 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…11,16 There are two theoretical models: The Zimm model taking into account hydrodynamic interactions between polymers in a mean field way predicts that k ) 0.65. Recent data that appear to be described satisfactorily by this model include those on polyacrylamide 17 and pectine, 26 whereas references to older data can be found in ref 11. The Rouse model, on the other hand, neglects hydrodynamic interactions and predicts that k ) 1.35.…”

Section: Discussionmentioning

confidence: 96%

“…These solidlike properties indicate the formation of a physical gel. , The critical phenomena that occur around a gel point are usually described by percolation theory. , The scaling laws which are predicted by this theory and to which our data can be compared are For the volume fraction dependence the exponent k of 0.59, observed for the sodium form of Nafion, corresponds reasonably well with what is observed in several other systems and predicted by theory. , There are two theoretical models: The Zimm model taking into account hydrodynamic interactions between polymers in a mean field way predicts that k = 0.65. Recent data that appear to be described satisfactorily by this model include those on polyacrylamide and pectine, whereas references to older data can be found in ref . The Rouse model, on the other hand, neglects hydrodynamic interactions and predicts that k = 1.35.…”

Section: Discussionmentioning

confidence: 97%

See 1 more Smart Citation

A Comparison of Mechanical and Electrical Percolation during the Gelling of Nafion Solutions

Cirkel

Okada

2000

Macromolecules

View full text Add to dashboard Cite

Rheological and impedance measurements are performed on Nafion solutions at relatively high concentration. The viscosity scales with the Nafion volume fraction as ηr ∝ φ0.59, up to φ = 2.5%. At higher fractions the viscosity diverges. At φ = 2.5% the storage modulus exhibits scaling behavior with the frequency (G‘ ∝ ω0.81), and the solution behaves as a gel. The results for the viscosity seem to fit the Zimm, rather than the Rouse, model. For the sodium form of Nafion the conductivity behaves qualitatively the same as the viscosity, with σ ∝ φ0.89, and can be described by a percolation network of conductors and superconductors. Above φ = 2.5% a sharp increase is observed, and the conductivity scales with the frequency as σ ∝ ω0.75. For Nafion in the proton form at volume fractions higher than 2.5% no sharp increase is observed in the conductivity, and the conductivity is independent of frequency. This indicates that in the proton form no electrical percolation takes place. It is discussed how these results can be used to improve the properties of recast membranes.

show abstract

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 97%

A Comparison of Mechanical and Electrical Percolation during the Gelling of Nafion Solutions

Cirkel

Okada

2000

Macromolecules

View full text Add to dashboard Cite

show abstract

“…The average cytosol is approximately 1.5 times more viscous than water [15] with intracellular areas with even greater values [16][17][18]. Polyacrylamide gel (PAG) viscosity can be adjusted by varying acrylamide concentration [19]. For this reason, we employ a phantom composed by PAGs that can reproduce the cytosol viscosity range [19] for a more realistic study of MNP systems.…”

Section: Introductionmentioning

confidence: 99%

“…Polyacrylamide gel (PAG) viscosity can be adjusted by varying acrylamide concentration [19]. For this reason, we employ a phantom composed by PAGs that can reproduce the cytosol viscosity range [19] for a more realistic study of MNP systems.…”

Section: Introductionmentioning

confidence: 99%

Thermographical Method to Assess the Performance of Magnetic Nanoparticles in Hyperthermia Experiments through Spatiotemporal Temperature Profiles

et al. 2023

View full text Add to dashboard Cite

The evaluation of the specific power absorption of magnetic nanoparticles (MNPs) for magnetic hyperthermia (MH) applications has been performed through either local temperature probing or magnetic measurements so far. Each of these methods has advantages and drawbacks, and the concurrent use of both techniques offers the most reliable results. In this work, we propose an alternative strategy based on thermographic images to obtain two-dimensional temperature maps that allow the determination of the power absorption and other relevant thermodynamic parameters in MH experiments in a noninvasive way. This procedure and analysis are convenient to determine the heating performance of MNPs under the viscous conditions of in vitro and in vivo assays and to follow the time evolution of the temperature spatial distribution in the sample simultaneously. For this purpose, iron-oxide MNPs with 25-nm average diameter are coated with glucose and dispersed into different 8% polyacrylamide gels, which serve as phantoms that emulate intracellular viscosity. Power absorption experiments are performed under ac magnetic fields (H = 32 kA/m; f = 350 kHz) and the temperature evolution of the sample is monitored through a commercial thermographic camera (resolution, 240 × 180 pixels; temperature accuracy, 2 K). To complement this simple setup, we design a program consisting of a detailed procedure for extracting graphical information from the video frames and obtaining spatiotemporal temperature profiles. The analysis of these profiles allows us to gather information on temperature, energy, power, and heat flux during the MH experiments. This method and analysis allows us to identify spatial inhomogeneities in samples, such as different local MNP density, which is extremely useful for the development of the therapy in vitro and the application in vivo where MNP aggregation is often present.

show abstract

“…The behavior of the magnetization near the Curie point is well described by the percolation theory (Stauffer & Aharony, 1992). In this connection, the macroscopic property of viscosity or elastic modulus of the gelation system has been measured, and the percolation theory has been successfully applied to the behavior of those macroscopic properties near the sol-gel transition point (Adam et al, 1985;Tokita & Hikichi, 1987, Tokita, 1989Yano et al, 1993 Kawabata et al., 1 996; Kjoniksen & Nysttom, 1996a;Durand et al, 1997). …”

mentioning

confidence: 97%

Dynamic Light Scattering Analysis on Critical Behavior of Cluster Size Distribution of Polyacrylamide and Agarose Solutions near the Sol-Gel Transition Point.

Fujii¹,

Yano²,

Kumagai³

et al. 2000

FSTR

Self Cite

View full text Add to dashboard Cite

The dynamic light scattering (DLS) method was applied to measure the cluster radii of polyacrylamide and agal~ ose solutions near the sol-gel transition point. In the case of polyacrylamide, primary clusters were formed first and secondary clusters on a larger scale were sequentially formed in the progress of the polymerization process. The zaverage radius of the secondary cluster near the sol-gel transition point increased divergently with an increase in acrylamide concentration to the transition point. By fitting the data with the scaling law, the sol-gel transition concentration and the critical exponent were determined to be 1.53 % and 0.84, respectively; The z-average radius of the agarose cluster also showed a tendency to diverge with an increase in concentration to the sol-gel transition point. With fitting by the scaling law, the sol-gel transition concentration and the critical exponent of the agarose solution were determined to be 4.5 x 10-2% and 0.92, respectively~ at 27.0'C. Thus, the percolation theory was proved to be effective to describe the cluster size distributions near the sol-gel transition point for both polyacrylamide and agarose solutions.Keywords: agarose, percolation, dynamic light scattering, correlation length, critical exponent Gels are widely used in the food industry, the analytical field, and the medical field. Agarose is one of the typical natural gelling substances frequently used in these fields. In studies on the microstructure of agarose molecule, electron microscopy (Am- sterdam et al., 1975;Waki et al., 1982;Sugiyama et al., 1994) and x-ray diffraction (Arnott et al., 1 974;Foord & Atkins, 1989) revealed that molecules are in the form of double helices interconnected with side-by-side associations.In the gelation process, it has been proposed that the sol-gel transition is analogous to the critical phenomena (De Gennes, 1979), such as magnetization phenomena near the Curie point.The gelation point is also believed to be a critical threshold: only a sol exists below the gelation point just as no magnetization exists above the Curie point. On the contrary, a gel exists above the gelation point and the magnetization is non-zero below the Curie point. The behavior of the magnetization near the Curie point is well described by the percolation theory (Stauffer & Aharony, 1992). In this connection, the macroscopic property of viscosity or elastic modulus of the gelation system has been measured, and the percolation theory has been successfully applied to the behavior of those macroscopic properties near the sol-gel transition point (Adam et al., 1985;Tokita & Hikichi, 1987, Tokita, 1989Yano et al., 1993 Kawabata et al., 1 996; Kjoniksen & Nysttom, 1996a;Durand et al., 1997).However, not only those macroscopic approaches but also a microscopic approach involving cluster-size distribution analysis is necessary to elucidate the mechanism of sol-gel transition.The cluster size distribution has been analyzed by GPC technique. However, it is difficult to apply this technique without t...

show abstract

Concentration Dependence of Mechanical Properties of Polyacrylamide near the Sol-Gel Transition Point

Cited by 14 publications

References 9 publications

A Comparison of Mechanical and Electrical Percolation during the Gelling of Nafion Solutions

A Comparison of Mechanical and Electrical Percolation during the Gelling of Nafion Solutions

Thermographical Method to Assess the Performance of Magnetic Nanoparticles in Hyperthermia Experiments through Spatiotemporal Temperature Profiles

Dynamic Light Scattering Analysis on Critical Behavior of Cluster Size Distribution of Polyacrylamide and Agarose Solutions near the Sol-Gel Transition Point.

Contact Info

Product

Resources

About