Swelling behavior, hydrogels

KGM and acrylic acid crosslinked by N,N-methylene bis-(acrylamide) 5-aminosalicylic acid Hydrogel Swelling behavior and degradation process showed that the gel was pH sensitive. Release rate of the model drug 5-ASA was proven to be controlled by swelling and degradation processes. The accumulative release percent of 5-ASA reached 95.19% after 36 h. [103]... 

Cationic hydrogel swelling behavior at low pH the drug is released due to the swelling of the polymer network. (Source-. Reprinted and adapted from Reyes eta ., 2013, copyright 2013, with permission from Elsevier B.V.)... 

Kamoun, E.A., Menzel, H., 2012. HES-HEMA nanocomposite polymer hydrogels swelling behavior and characterization. Journal of Polymer Research 19, 1—14. 

The swelling behavior of hydrogels in solutions of multivalent ions capable to associate with the network-fixed charges, e.g., Cu2+, substantially differs from that described above, viz. the collapse of gels takes place [107]. As a result of this... 

These examples show once again that the network-fixed charges play an important role in the swelling behavior of hydrogels. 

The swelling pattern considered above allows us to understand the peculiarities of the behavior of SAH and the effects encountered during their application. The kinetic aspects of swelling seem to be as important as the thermodynamics of this process. Therefore, we shall touch upon some problems concerning the kinetics of hydrogel swelling and deswelling. 

The previous analysis of SAH behavior in the soil clearly shows that their application for improving the water-holding capacity is not universal. Hydrogel swelling in a porous, partially salinized medium is affected by numerous factors, most often negative, and therefore a rational application of SAH demands an accurate consideration of these factors. It is evident that certain principles for adjustment of hydrogels to physical and chemical soil parameters, as well as appropriate laboratory tests and calculation algorithm systems should be worked out. 

Baker, JP Hong, LH Blanch, HW Prausnitz, JM, Effect of Initial Total Monomer Concentration on the Swelling Behavior of Cationic Acrylamide-Based Hydrogels, Macromolecules 27, 1446, 1994. 

The lack of quantitative success of the theory presented in the previous section is primarily the result of inadequacies in the mixing and elasticity terms. Sophisticated theoretical expressions are available which afford much improved predictions of swelling behavior. However, even these theories are not particularly successful when applied to hydrogels. Here the limitations of the theory presented in Section III.A.l will be identified. 

DC Harsh, SH Gehrke. Modeling swelling behavior of cellulose ether hydrogels. In M El-Nokaly, D Piatt, B Charpentier, eds. Polymeric Delivery Systems. ACS Symp Ser 520. Washington, DC American Chemical Society, 1993, pp 105-134. 

Another class of environmentally sensitive materials that are being targeted for use in drug delivery applications is thermally sensitive polymers. This type of hydrogel exhibits temperature-sensitive swelling behavior... 

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. 

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],... 

Kim B, Flamme KL, Peppas NA (2003) Dynamic swelling behavior of pH-sensitive anionic hydrogels for protein delivery. J Appl Polym Sci 89 1606-1613... 

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. 

Tuning the Swelling Behavior of PNIPAAm Hydrogel Layers... 

The thin NIPAAm hydrogel layers were covalently attached to the surface, therefore the swelling was confined to one direction perpendicular to the substrate. The degree of anisotropy was calculated from ratio of l/0p and swelling ratio. This ratio was found to be between 1.2-1.3. Such a study describing the effect of hydrophilic comonomer on Tc of PNIPAAm provides an opportunity to formulate thermoresponsive hydrogel layers with desired transition temperature and swelling behavior for various applications. 

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