Unassociated Molecular Chains in Physically Crosslinked Gellan Gels

Tanaka, Shimon; Nishinari, Katsuyoshi

doi:10.1295/polymj.pj2006149

Cited by 24 publications

(15 citation statements)

References 41 publications

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“…Therefore, the actual W d between the initial and final dehydrations could not be obtained ( W t / W d could not be determined). However, it is evident that the final W t / W d is larger than the initial one, which indicated that the swelling ratio increased by polymer elution during the repeated water exchanges 19. As shown in this figure, W t decreased and became constant after 20 days, which indicated that the elution almost stopped after 20 days.…”

Section: Resultsmentioning

confidence: 76%

A simple method to obtain a swollen PVA gel crosslinked by hydrogen bonds

Otsuka

Suzuki

2009

J of Applied Polymer Sci

115

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A simple method to obtain a physically crosslinked poly(vinyl alcohol) (PVA) hydrogel is reported. In this technique, the PVA solution in pure water was simply cast at room temperature without using any additional chemical. The gelation proceeded during the dehydration after casting the PVA solution into a mold. After the completion of gelation, the swelling ratio of the gel in its equilibrium was measured whenever the solvent water was repeatedly exchanged. The weight gradually decreased due to the elution of non-crosslinked polymers into the solvent, and became constant after sufficient water exchange. The measurements using a Fourier Transform infrared spectroscopy and an X-ray diffraction suggested that the crosslinks due to hydrogen bonds and microcrystals were formed during the dehydration process of the PVA solution. We concluded that the sample obtained by the present method is a physically crosslinked polymer network, insoluble in water, i.e., a swollen gel in water.

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Section: Resultsmentioning

confidence: 76%

A simple method to obtain a swollen PVA gel crosslinked by hydrogen bonds

Otsuka

Suzuki

2009

J of Applied Polymer Sci

115

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“…Although 0.15wt% kappa-carrageenan forms a gel in 0.2mol/dm 3 KCl, ten times more concentrated 1.5wt% kappa-carrageenan does not form a gel in 0.2mol/dm 3 NaI where kappa-carrageenan molecules form helices but these helices donot aggregate to form junction zones.…”

Section: Gelation Pointmentioning

confidence: 97%

“…This definition is limited to chemically crosslinked gels and excludes physical gels made by secondary molecular forces such as hydrogen bonds and hydrophobic interactions. It was found recently that some molecular chains in a gellan gel release out from the gel when it is immersed in a solvent such as water or salt solutions [3,4]. After a long time, the gel swells infinitely, and disperses completely in a great amount of water.…”

Section: Definition Of a Gelmentioning

confidence: 99%

Some Thoughts on The Definition of a Gel

Nishinari

2009

Gels: Structures, Properties, and Functions

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To avoid the confusion of the concept of a gel frequently encountered in daily markets of food, cosmetics, and other industrial products, the definition of a gel is revisited. Recent proposals of the definition of a gel are overviewed, and classifications of various gels from different points of view are described. Discussion is mainly focused on the gel-sol transition and the difference between the structured liquid and the gel, and the classification of gels by temperature dependence of elastic modulus. Finally, the definition of a gel is proposed as a working hypothesis from rheological and structural view points.

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“…[8][9][10][11] This elution phenomenon is characteristic of physically cross-linked gels. Recently, the elution from PVA cast gels has been measured quantitatively.…”

Section: Introductionmentioning

confidence: 99%

A Novel Method to Control the Elution Behavior of PVA Cast Gels

Sasaki

Suzuki

2015

Macromolecular Symposia

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Summary: Poly(vinyl alcohol) (PVA) gels, prepared by a cast-drying method, show excellent swelling and mechanical properties. However, the elution of polymers from such gels is one of the major hindrances for practical applications. In this study, PVA cast gels were prepared from a PVA powder, with a high degree of polymerization and hydrolysis, under different temperatures and humidities. The swelling ratio, elution ratio, crystallinity, and microcrystallite size were evaluated, and these were compared with each other. The lowest elution rate (<1%) was obtained under conditions of high drying temperature and high humidity. This indicates that polymer elution can be suppressed by controlling the size, number, and distribution of the microcrystallites.

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Unassociated Molecular Chains in Physically Crosslinked Gellan Gels

Cited by 24 publications

References 41 publications

A simple method to obtain a swollen PVA gel crosslinked by hydrogen bonds

A simple method to obtain a swollen PVA gel crosslinked by hydrogen bonds

Some Thoughts on The Definition of a Gel

A Novel Method to Control the Elution Behavior of PVA Cast Gels

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