title: Increased Hydrogel Swelling Induced by Absorption of Small Molecules.
abstract: The water and small molecule uptake behavior of amphiphilic diacrylate terminated poly(dimethylsiloxane) (PDMSDA)/poly(ethylene glycol diacrylate) (PEGDA) cross-linked hydrogels were studied using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. These hydrogel networks absorbed more water as the PEGDA content of the network increased. In contrast to typical osmotic deswelling behavior that occurs when liquid water equilibrated hydrogels are immersed in small molecule solutions with water activities less than unity, water-swollen gels immersed in 2-acrylamido-2-methylpropanesulfonic acid (AMPS-H) solutions rapidly regained their water content within 4 min following an initial deswelling response. In situ ATR-FTIR analysis of the hydrogel film during the dynamic swelling experiment indicated that small molecule absorption into the gel played an important role in inducing gel reswelling in low water activity solutions. This aspect of polymer gel water uptake and interaction with small molecules is important for optimizing hydrogel coatings and hydrophilic polymer applications where there is an interaction between the internal chemical structure of the gel and electrolytes or other molecules in solution.
authors.affiliation: Department of Materials Science and Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Changwoo
authors.initials: C
authors.lastname: Nam
authors.affiliation: Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Tawanda J
authors.initials: TJ
authors.lastname: Zimudzi
authors.affiliation: Department of Chemical Engineering, The University of Virginia , Charlottesville, Virginia 22904, United States.
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Geise
authors.affiliation: Department of Materials Science and Engineering, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Hickner
keywords: ATR-FTIR spectroscopy; amphiphilic; hydrogel; sulfonic acid; water uptake