Synthesis, equilibrium swelling, kinetics, permeability and applications of environmentally responsive gels

Gehrke, Stevin H.

doi:10.1007/bfb0021130

Cited by 236 publications

(128 citation statements)

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“…−p (27) In this section, the effect of external salt concentration ([Re]) on the binding of target molecules to the gel is presented. The gel system is similar to that used in the studies on adsorber dependence.…”

Section: Salt Concentration Dependencementioning

confidence: 99%

Multiple point adsorption in a heteropolymer gel and the Tanaka approach to imprinting: experiment and theory

Ito

Chuang

Alvarez‐Lorenzo

et al. 2003

Progress in Polymer Science

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Heteropolymer gels can be engineered to release specific molecules into or absorb molecules from a surrounding solution. This remarkable ability is the basis for developing gel applications in extensive areas such as drug delivery, waste cleanup, and catalysis. Furthermore, gels are a model system for proteins, many of whose properties they can be created to mimic. A key aspect of gels is their volume phase transition, which provides a macroscopic mechanism for effecting microscopic changes. The phase transition allows one to control the gel's affinity for target molecules through tiny changes in the solution temperature, salt concentration, pH, or the like. We summarize recent experiments that systematically characterize the gel affinity as a function of adsorbing monomer concentration, solution salt concentration, and cross-linker concentration, on both sides of the phase transition. We provide a physical theory that explains the results and discuss enhancements via imprinting.

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Section: Salt Concentration Dependencementioning

confidence: 99%

Multiple point adsorption in a heteropolymer gel and the Tanaka approach to imprinting: experiment and theory

Ito

Chuang

Alvarez‐Lorenzo

et al. 2003

Progress in Polymer Science

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“…PMAA hydrogel is not temperature sensitive because PMAA polymer is supposed to not exhibit a solubility phase transition at the experimentally achieved thermodynamic conditions. Data are adapted from [16][17][18].…”

Section: Effectors Of Volume Change In Hydrogelsmentioning

confidence: 99%

“…The studies [16,19,20] show that increased cross-linking may significantly decrease swelling ability of hydrogel, especially, below Tc, but has a little effect on the value of Tc. These conclusions agree with our results (Figure 4).…”

Section: Effectors Of Volume Change In Hydrogelsmentioning

confidence: 99%

Hydrogel Films on Optical Fiber Core: Properties, Challenges, and Prospects for Future Applications

Казаков¹

2012

New Polymers for Special Applications

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There are experimental evidences [29][30][31] of de-swelling effects of different monovalent (Li + , Na + , K + , Cs + ) and divalent (Ca 2+ , Mg 2+ , Sr 2+ , Ba 2 ) ions in hydrogels of different chemical nature, including the biologically relevant gels [32] and cross-linked DNA [33]. Interestingly, at the same molar ratios of divalent to monovalent cations, ~ 1 mM to 30 mM, respectively, similar volume changes were observed in biological polyelectrolyte systems during physiological processes like nerve excitation, musle contraction, and cell locomotion [34][35][36][37][38][39][40].Surfactants. The extensive theoretical [41][42][43] and experimental [44][45][46][47][48] studies have shown that addition of anionic, cationic, and nonionic surfactants to the solution containing a gel can also influence the volume phase transition temperature and swelling degree of hydrogels depending on their hydrophobicity and charge of the polymer network. In general, addition of anionic or cationic surfactant to the solution of nonionic hydrogel rises the transition temperature as well as the swelling range, whereas the nonionic surfactant does not affect the transition temperature or the volume change. The surfactants with ionic head groups convert the neutral hydrogels to a polyelectrolyte gels when bind to the nonionic polymer networks, so that the transition temperatures elevate due to introduction of additional osmotic pressure by ionization. The changes in the volume phase transition are also dependent on the length of hydrophobic tail of ionic surfactants and the critical concentration of micelle formation. Indeed, it was found [45] that the transition temperature of nonionic poly(acryloyl-L-proline methyl ester) hydrogels increases more drastically in solutions of anionic sodium alkane sulfonate surfactants with the higher number of methylene units in the tail and at lower concentration than those with the shorter tails. The other interesting findings are [47]: (i) the amount of an ionic surfactant bound onto the swollen network of the nonionic PNIPA hydrogel is much greater than that to the collapsed

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“…Entre las propiedades de los hidrogeles, la temperatura de transición de volumen de fase (TTPV), ha atraído gran atención desde su descubrimiento [5,6] . El estudio de la transición de volumen de fase fue iniciado por la predicción teórica de Dusek y Patterson [7,8] . Estos autores sugirieron la posibilidad del cambio discontinuo de volumen de un gel (TTPV), basándose en la analogía de la transición de ovillo-glóbulo ("coil-globule") de polímeros en solución, la cual fue predicha por Pitsyn [9] .…”

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Síntesis de hidrogeles de acrilamida en soluciones acuosas de etanol

Sánchez

Ortega

2014

Polímeros

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Resumen: En el presente trabajo se realizó la polimerización de acrilamida en soluciones acuosas de etanol, variando la composición del etanol en la solución; obteniéndose tanto nanogeles como macrogeles. Se determinó la capacidad de absorber agua de los macrogeles; obteniéndose materiales que tienen una capacidad de absorber desde 40 y hasta 90 gramos de agua por gramo de xerogel y el tamaño de partícula de los nanogeles fueron desde 71 nm y hasta 463 nm.Palabras clave: Acrilamida, etanol, nanoparticulas. Polymerization of Acrylamide Hydrogels in Aqueous EthanolAbstract: The polymerization of acrylamide was performed in aqueous ethanol solutions, varying the concentration of ethanol in the solution; obtaining both nanogels as macrogels. The water absorbing capacity of the macrogels were found; obtaining materials with a capacity to absorb from 40 to 90 g of water per gram of xerogel and the particle size of the nanogels are at values ranging from 71 nm to 463 nm. Keywords: Acrylamide, etanol, nanoparticles.Autor para correo: Jorge Alberto Aortés Artega, Departamento de Química, Universidad de Guadalajara, Boul. M. García Barragán # 1451, Guadalajara, Jalisco 44430, México, e-mail: jorcortes@hotmail.com IntroducciónIncrementar la capacidad de absorber agua en los hidrogeles se ha convertido en tema de estudio en los últimos años. Los hidrogeles son redes poliméricas que se hinchan considerablemente en presencia de agua manteniendo su forma hasta alcanzar un equilibrio fisicoquímico [1] . El carácter hidrófilo de estos materiales, se debe a la presencia de grupos compatibles con el agua, tales como -OH, -COOH, -CONH2, -SO3H. Por otro lado, en estado deshidratado, un hidrogel se denomina xerogel y tiene estructura cristalina [2] . Las propiedades de los hidrogeles, permiten su utilización en diferentes campos [3,4] . Entre las propiedades de los hidrogeles, la temperatura de transición de volumen de fase (TTPV), ha atraído gran atención desde su descubrimiento [5,6] . El estudio de la transición de volumen de fase fue iniciado por la predicción teórica de Dusek y Patterson [7,8] . Estos autores sugirieron la posibilidad del cambio discontinuo de volumen de un gel (TTPV), basándose en la analogía de la transición de ovillo-glóbulo ("coil-globule") de polímeros en solución, la cual fue predicha por Pitsyn [9] . La transición de fase en volumen fue descubierta experimentalmente en 1978 por Tanaka [10] , en un gel parcialmente ionizado de poliacrilamida en una mezcla de acetona-agua. Esta transición de fase se observó no sólo al cambiar la composición del solvente, sino también al variar la temperatura, la concentración de iones, el pH o el campo eléctrico. Se ha encontrado que los geles de poliacrilamida poli(AM) no absorben etanol, sin embargo el monómero acrilamida es soluble en soluciones acuosas de etanol e inclusive en etanol [11] . Por lo que se puede esperar que hidrogeles preparados con este monómero presenten esta transición al incrementar la concentración de etanol en la solución. La capacidad de absor...

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Synthesis, equilibrium swelling, kinetics, permeability and applications of environmentally responsive gels

Cited by 236 publications

References 109 publications

Multiple point adsorption in a heteropolymer gel and the Tanaka approach to imprinting: experiment and theory

Multiple point adsorption in a heteropolymer gel and the Tanaka approach to imprinting: experiment and theory

Hydrogel Films on Optical Fiber Core: Properties, Challenges, and Prospects for Future Applications

Síntesis de hidrogeles de acrilamida en soluciones acuosas de etanol

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