Hydrogels ionic

Oppermann, W., Swelling Behavior and Elastic Properties of Ionic Hydrogels, in Polyelectrolyte Gels Properties, Preparation, and Applications (R. S. Harland and R. K. Prud homme Eds.), pp. 159-170. American Chemical Society, Washington (1992). 

Several factors affect the swelling of ionic hydrogels. Peppas and Khare [12] indicated some of the parameters that affect this swelling behavior. 

Nature of counterions counterions of higher valence are more strongly attracted to the gel phase in ionic hydrogels. These ions are preferred by the gel because the concentration of counterions needed inside the gel decreases. 

Other models that have been proposed to describe the swelling behavior of ionic hydrogels include that of Prausnitz and collaborators [16] and Konak and Bansil [17],... 

Amende MT, Hariharan D, Peppas NA. Factors influencing drug and protein-transport and release from ionic hydrogels. Reactive Polymers 1995, 25, 127-137. 

Oppermann, W. (1992). Swelling behavior and elastic properties of ionic hydrogels. In Polyelectrolyte Gels, Harland, R. S., and Prud homme, R. K. (Eds.), ACS Symposium Series 480, pp. 159-170. Am. Chem. Soc., Washington, DC. 

Since ionic hydrogels are highly swollen in water, their swelling equilibrium is mainly determined by the mixing entropy of the counterions, which is balanced by the gel s rubberUke elasticity. According to the theory of rubber elasticity of... 

In order for an ionic hydrogel-like material to be electroactive, several components are necessary ... 

A completely different swelling behavior is observed for ionic hydrogels formed in solutions of oppositely charged surfactants. Figure 8a, b shows of HM PAAc hydrogels formed in CTAB-NaBr solutions plotted against the swelling time in... 

Ionic hydrogels formed in oppositely charged surfactant solutions exhibit a significant enhancement of their mechanical properties when they are immersed in water [42], For instance, Fig. 19 shows the stress-strain data of HM PAAc gels... 

Hydrophobic ally modified ionic hydrogels formed in oppositely charged surfactant solutions exhibit frequency-dependent dynamic moduli if they are in equilibrium in water after extraction of free surfactant micelles. This is a result of complex formation between the ionic polymer and the oppositely charged surfactant, leading to polymer-bound surfactant counterions in the hydrogels. 

These observations Aat Ae membrane becomes transparent and Aat the size of microcapsules increases in alkaline medium suggest that poly(L-lysine-a/t-terephthalic acid) microcapsule membranes have a gel-like structure and undergo a volume transition at a pH value between 4 and 6, as usually seen in ionic hydrogels. This pH-driven volume transition is considered to be due to the change of Ae charge density in Ae microcapsule membrane. 

Figure 9.31 lllusttation of the first-order phase transition in ionic hydrogels. The extent of swelling may change dramatically with environmental factors, as shown. 

Orlov Y, Xu X, Maurer G (2006) Equilibrium swelling of n-isopropylacrylamide based ionic hydrogels in aqueous solutions of organic solvents comparison of experiment with theory. Fluid Phase Equilib 249(l-2) 6-16... 

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