Dynamic and static light scattering by aqueous polyacrylamide gels

Joosten, J. G. H.; McCarthy, Jennifer L.; Pusey, P. N.

doi:10.1021/ma00025a021

Cited by 253 publications

(319 citation statements)

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“…PA gels are created through copolymerization of acrylamide and bisacrylamide. Light scattering has shown that PA gels have a bimodal distribution of pore sizes [26][27][28][29]. This occurs because bisacrylamide has a greater reaction rate with itself than with acrylamide.…”

Section: Gel Preparationmentioning

confidence: 99%

Influence of branch length asymmetry on the electrophoretic mobility of rigid rod‐like DNA

et al. 2004

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The electrophoretic mobility of three-arm asymmetric star DNA molecules, produced by incorporating a short DNA branch at the midpoint of rigid-rod linear DNA fragments, is investigated in polyacrylamide gels. We determine how long the added branch must be to separate asymmetric star DNA from linear DNA with the same total molecular weight. This work focuses on two different geometric progressions of small DNA molecules. First, branches of increasing length were introduced at the center of a linear DNA fragment of constant length. At a given gel concentration, we find that relatively small branch lengths are enough to cause a detectable reduction in electrophoretic mobility. The second geometric progression starts with a small branch on a linear DNA fragment. As the length of this branch is increased, the DNA backbone length is decreased such that the total molar mass of the molecule remains constant. The branch length was then increased until the asymmetric branched molecule becomes a symmetric three-arm star polymer, allowing the effect of molecular topology on mobility to be studied independent of size effects. DNA molecules with very short branches have a mobility smaller than linear DNA of identical molar mass. The reason for this change in mobility when branching is introduced is not known, however, we explore two possible explanations in this article. (i) The branched DNA could have a greater interaction with the gel than linear DNA, causing it to move slower; (ii) the linear DNA could have modes of motion or access to pores that are unavailable to the branched DNA.

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Section: Gel Preparationmentioning

confidence: 99%

Influence of branch length asymmetry on the electrophoretic mobility of rigid rod‐like DNA

et al. 2004

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“…Joosten et al 44 reported an increase of D with increasing polymer concentration for reactor-batch acrylamide gels. The reported values of D's are in good agreement with our results.…”

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confidence: 99%

Universality and Specificity of Polymer Gels Viewed by Scattering Methods

Shibayama¹

2006

Bulletin of the Chemical Society of Japan

106

112

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Concentration fluctuations in polymer gels are composed of dynamic thermal fluctuations and frozen inhomogeneities. Particularly, the latter is a characteristic of gels and is due to cross-linking. The frozen inhomogeneities manifest unique properties in polymer gels. Speckle patterns are commonly observed in gels. The time-correlation function of the scattering intensity entails a power-law behavior at the sol-gel transition. The appearance of speckle patterns is related to the nonergodicity of gels, and the power-law behavior corresponds to the self-similarity of clusters at the gelation threshold. In this review, it will be demonstrated that light scattering is one of the most powerful tools for structure characterization of polymer gels. Then, the universality and specificity of polymer gels will be examined for various types of gels, including physical gels, composite gels, and gelators.

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“…Since the autocorrelation function and the power spectrum of a signal are Fourier transform pairs, 5 the autocorrelation of the time intensity signal at each pixel location was calculated by taking the inverse Fourier transform of its power spectrum. Treating the cell samples as nonergodic media, an intermediate scattering function (ISF) was calculated from the intensity autocorrelation function using the "heterodyne approach" described by Joosten et al 6 This technique removes the contribution from the static scattering components to the fluctuating signal. An average decorrelation time (DT) was calculated for each data set by measuring the half width of the ISF at half its maximum value.…”

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confidence: 99%