Swelling pressure equilibrium of physical networks in the field of an analytical ultracentrifuge

Holtus, G.; Borchard, W.

doi:10.1007/bf01496936

Cited by 18 publications

(8 citation statements)

References 12 publications

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“…6 was fiist explained by arguing that the networks are inhomogeneous in the corresponding range of initial concentrations [16,17]. There are possibly higher crosslinked regions as well as those with a lower crosslinking density compared with that of a homogeneous network.…”

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confidence: 99%

Characterization of thermo‐reversible gels by means of sedimentation equilibria

Borchard

Cölfen

1992

Makromolekulare Chemie. Macromolecular Symposia

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This paper describes the deformation of gels in a centrifugal field leading to a continuous equilibrium. A gel is considered to be a binary mixture of crosslinked polymer and solvent and is assumed to remain isotropic during the deformation. From the equation for the osmotically effective pressure, called swelling pressure, the thermodynamic properties of a gel can be calculated. For highly swollen gels the expression of Svedberg and Pedersen is obtained. It is shown that the complete concentration dependence of the swelling pressure in the concentration range of the maximally swollen gel up to that at the cell bottom can be measured in a single equilibrium experiment. The homogeneity of weakly crosslinked gels can be examined by means of the method described. Soluble parts which are not incorporated into the polymer network can also be detected if they are present. From the swelling pressure-concentration curves it is possible to derive the thermodynamic properties of the physically crosslinked gelatidwater gels that were investigated. These gels can be described by means of a slightly modified Flory-Huggins equation with an interaction parameter xw in the weight fraction scale, which depends linearly on concentration. The interaction parameters show a dependence on concentration which is explained by an increased branching and crosslinking of the polymer with increasing initial polymer concentration of the gels. At low initial polymer concentration, the primary chains have to aggregate to build up relatively long chains between the network junctions. The static shear modulus G which can be calculated from the network term has the same order of magnitude as the real part of the complex shear modulus which is measured at low frequency.

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confidence: 99%

Characterization of thermo‐reversible gels by means of sedimentation equilibria

Borchard

Cölfen

1992

Makromolekulare Chemie. Macromolecular Symposia

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“…The first improvements in the experimental set-up for sedimentation equilibrium experiments with gels were published by Holtus and Borchard using a Beckman Model E ultracentrifuge (Hollus and Borchard, 1989;Holtus, 1990). These improvements concern the modification of the Schlieren optical system to an off-line data capture system with a modulable laser light source to enable the application of 6-hole rotors due to the extreme experimental durations of about three weeks.…”

Section: Characterization Of Biopolymer Gels Alld Microgeis 113mentioning

confidence: 99%

Analytical Ultracentrifuge Technologies for the Characterization of Biopolymer Gels and Microgels

Cölfen¹

1999

Biotechnology and Genetic Engineering Reviews

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“…Nowadays, swelling is one of the basic scientific pillars in biology, polymer and colloid science where corresponding studies contribute a great deal to our understanding in these areas. Swelling pressure studies have quite a long history [3,5,[7][8][9][10][11]. This is by far not a complete list of references but only a few marking essential steps in this development.…”

Section: Introductionmentioning

confidence: 99%

“…These are examples of measuring the swelling pressure directly by pressure gauges (manometers) or by means of ultracentrifugation. The latter method has the advantage that composition dependence of the swelling pressure is obtained in just a single experiment [9]. Progressing miniaturization of devices for pressure measurements stimulated during the last decade the development of small sensors utilizing the swelling pressure of gels [12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

How much weighs the swelling pressure

Höhne

Tauer

2014

Colloid Polym Sci

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We are presenting a new method to study the swelling of gels by following the apparent weight increase during confined swelling. This method, compared to other procedures, is characterized by its simplicity and versatility to study the influence of the experimental conditions such as composition of the swelling agent and temperature. Examples are given for poly(acrylic acid) and poly(N-isopropyl acrylamide) hydrogels and the influence of ethanol content, pH, and temperature in the water pool.

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Swelling pressure equilibrium of physical networks in the field of an analytical ultracentrifuge

Cited by 18 publications

References 12 publications

Characterization of thermo‐reversible gels by means of sedimentation equilibria

Characterization of thermo‐reversible gels by means of sedimentation equilibria

Analytical Ultracentrifuge Technologies for the Characterization of Biopolymer Gels and Microgels

How much weighs the swelling pressure

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