Freezing as a path to build macroporous structures: Superfast responsive polyacrylamide hydrogels |
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Affiliation: | 1. \"Petru Poni\" Institute of Macromolecular Chemistry, Functional Polymers Department, Iasi, Romania;2. Istanbul Technical University, Department of Chemistry, Maslak 34469, Istanbul, Turkey |
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Abstract: | Macroporous polyacrylamide (PAAm) hydrogels were prepared from acrylamide monomer and N,N′-methylene(bis)acrylamide (BAAm) crosslinker in frozen aqueous solutions. It was found that the swelling properties and the elastic behavior of the hydrogels drastically change at a gel preparation temperature of ?6 °C. The hydrogels prepared below ?6 °C exhibit a heterogeneous morphology consisting of pores of sizes 10–70 μm, while those formed at higher temperatures have a non-porous structure. PAAm networks with largest pores were obtained at ?18 °C. The pore size of the networks increased while the thickness of the pore walls decreased by decreasing the monomer concentration. The hydrogels formed below ?6 °C exhibit superfast swelling and deswelling properties as well as reversible swelling–deswelling cycles in water and in acetone, respectively. |
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