Phase transitions in ionic gels

Tanaka, Toyoichi; Sun, Shao‐Tang; Nishio, Izumi; Swislow, Gerald; Shah, Arati

doi:10.1080/00150198008209494

Cited by 99 publications

(130 citation statements)

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“…A localized enlargement of the pores could then allow access of the hydrolase to substrate. Artificial gels possess remarkable capacity for reversible volume changes induced by small changes in temperature, type and concentration of salts, pH, and electrical fields (Hirokawa et al, 1985;Katayama and Ohata, 1985;Ohmine and Tanaka, 1982;Tanaka et a/., 1980. With anionic gels, positively charged salts bind to the surface and cause a localized osmotic shrinkage.…”

Section: Changes In Structure During Cell Elongationmentioning

confidence: 99%

Structural models of primary cell walls in flowering plants: consistency of molecular structure with the physical properties of the walls during growth

1993

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SummaryAdvances in determination of polymer structure and in preservation of structure for electron microscopy provide the best view to date of how polysaccharides and structural proteins are organized into plant cell walls. The walls that form and partition dividing cells are modified chemically and structurally from the walls expanding to provide a cell with its functional form. In grasses, the chemical structure of the wall differs from that of all other flowering plant species that have been examined. Nevertheless, both types of wall must conform to the same physical laws. Cell expansion occurs via strictly regulated reorientation of each of the wall's components that first permits the wall to stretch in specific directions and then lock into final shape. This review integrates information on the chemical structure of individual polymers with data obtained from new techniques used to probe the arrangement of the polymers within the walls of individual cells. We provide structural models of two distinct types of walls in flowering plants consistent with the physical properties of the wall and its components.

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Section: Changes In Structure During Cell Elongationmentioning

confidence: 99%

Structural models of primary cell walls in flowering plants: consistency of molecular structure with the physical properties of the walls during growth

1993

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“…1,2 Some hydrogels undergo changes in swelling or network structure in response to external stimuli such as pH, 3 temperature, 4,5 light, 6,7 ionic strength 3 and electric field. 8 The development of such materials has recently received considerable interest due to the potential applications in a vast range of areas.…”

Section: Introductionmentioning

confidence: 99%

Thermoresponsive Polymer Micropatterns Fabricated by Dip-Pen Nanolithography for a Highly Controllable Substrate with Potential Cellular Applications

Laing

Suriano²,

Lamprou

et al. 2016

ACS Appl. Mater. Interfaces

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We report a novel approach for patterning thermoresponsive hydrogels based on N,Ndiethylacrylamide (DEAAm) and bifunctional Jeffamine ED-600 by dip-pen nanolithography (DPN). The direct writing of micron-sized thermoresponsive polymer spots was achieved with efficient control over feature size. A Jeffamine-based ink prepared through the combination of organic polymers, such as DEAAm, in an inorganic silica network was used to print thermosensitive arrays on a thiol-silanised silicon oxide substrate. The use of a Jeffamine hydrogel, acting as a carrier matrix, allowed a reduction in the evaporation of ink molecules with high volatility, such as DEAAm, and facilitated the transfer of ink from tip to substrate. The thermoresponsive behaviour of polymer arrays which swell/de-swell in aqueous solution in response to a change in temperature was successfully characterised by atomic force microscopy (AFM) and Raman spectroscopy: a thermally-induced change in height and hydration state was observed, respectively. Finally, we demonstrate that cells can adhere to and interact with these dynamic features and exhibit a change in behaviour when cultured on the substrates above and below the transition temperature of the Jeffamine/DEAAm thermoresponsive hydrogels. This 3 demonstrates the potential of these micropatterned hydrogels to act as a controllable surface for cell growth.

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“…4, 38), and gels in mixed-solvent solutions (ref. 4). A satisfactory theoretical description has not yet been obtained for the large volume transitions obserVed in these systems.…”

Section: Discussionmentioning

confidence: 99%

Molecular Thermodynamics of Aqueous Polymers and Gels

Blanch

Prausnitz

1990

Absorbent Polymer Technology

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DivisionTo be published as a chapter in Absorbent Polymer Technology, L. Brannon-Peppas and R. Harland, Eds., Elsevier Science Publishers B.V., Amsterdam, The Netherlands, Fall 1990 Molecular Thermodynamics of Aqueous Polymers and Gels For Reference Fe bruary 1990 Not to be taken from this room SUMMARYThe phase behavior of aqueous polymer solutions and gels is often sensitive to prevailing conditions such as temperature, pH, ionic strength or solvent composition. For crosslinked polymer gels, this solution-sensitivity is indicated by large changes in gel volume in response to small changes in solution conditions. This chapter reviews recent work directed at developing a molecular-thermodynamic description of phase behavior in aqueous polymer systems. A theoretical description for hydrogel swelling equilibria correlates systematic experimental data obtained for model systems. Novel molecular-simulation studies of isolated polyelectrolytes provide detailed information on the relationship between expansion of polyelectrolytes in solution and pertinent parameters that characterize polymer and solution properties. INTRODUCTIONAqueous polymer systems have applications in a variety of areas including specialty chemicals, pharmaceuticals, personal-care products, enhanced-oil-recovery processes, and biomedical uses. In many applications, the polymer is in crosslinked form, i.e., as a hydrogel. Hydrogels are often superabsorbent, imbibing many times their weight in water. The large water affinity of certain hydrogels makes them particularly attractive for applications where biocompatability is important (e.g., for contact lenses or biological implants), and in applications where large water absorbency is desired (e.g., in disposable diapers, or agriculture in arid climates). Superabsorbent materials comprise an active area of materials research; hydrogels represent an important class of such materials.The superabsorbent nature of a hydrogel is related to the hydrophilicity of the chains comprising the polymer network. For example, superabsorbent gels are often made of crosslinked polyelectrolytes. Polyelectrolytes expand significantly in solution as shown by their intrinsic viscosity and excluded-volume properties. The hydrophilic nature of the individual chains gives a gel with high water affinity.The nature of the polymer and the conditions of the solvent determine the configurational (or expansion) behavior of isolated polymers in solution, in addition to the phase behavior (solubility properties) of concentrated polymer solutions. For example, it has been long known that temperature change can induce liquid-liquid phase separation in aqueous polymer solutions, and cOil-globule transitions for isolated polymers in solution (ref. 1). Similarly, certain hydrogels have recently been shown to

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Phase transitions in ionic gels

Cited by 99 publications

References 0 publications

Structural models of primary cell walls in flowering plants: consistency of molecular structure with the physical properties of the walls during growth

Structural models of primary cell walls in flowering plants: consistency of molecular structure with the physical properties of the walls during growth

Thermoresponsive Polymer Micropatterns Fabricated by Dip-Pen Nanolithography for a Highly Controllable Substrate with Potential Cellular Applications

Molecular Thermodynamics of Aqueous Polymers and Gels

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