title: Surfactant and metal ion effects on the mechanical properties of alginate hydrogels.
abstract: This paper addresses the controlled variation of the mechanical properties of alginate gel beads by changing the alginate concentration or by adding different surfactants or cross-linking cations. Alginate beads containing nonionic Brij 35 or anionic sodium dodecyl sulfate (SDS) surfactants were prepared with two different types of cations (Ca2+, Ba2+) as crosslinkers. Compression measurements were performed to investigate the effect of the surfactant and cation types and their concentrations on the Young's modulus of alginate beads. The Young's modulus was determined by using Hertz theory. For all types of alginate gel beads the Young's modulus showed an increasing value for increasing alginate contents. Addition of the anionic surfactant SDS increases the Young's modulus of the alginate beads while the addition of non-ionic surfactant Brij 35 leads to a decrease in Young's modulus. This opposite behavior is related to the contrary effect of both surfactants on the charge of the alginate beads. When Ba2+ions were used as crosslinker cation, the Young's modulus of the beads with the surfactant SDS was found to be approximately two times higher than the modulus of beads with the surfactant Brij 35. An ion specific effect was found for the crosslinking ability of divalent cations.
authors.affiliation: Istanbul Technical University, Faculty of Science and Letters, Maslak 34469 Istanbul, Turkey; Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 124, 10623 Berlin, Germany.
authors.forename: Hakan
authors.initials: H
authors.lastname: Kaygusuz
authors.affiliation: Piri Reis University, Faculty of Science and Letters, Tuzla 34940 Istanbul, Turkey.
authors.forename: Gülşen Akın
authors.initials: GA
authors.lastname: Evingür
authors.affiliation: Kadir Has University, Faculty of Science and Letters, Cibali, 34083 Istanbul, Turkey.
authors.forename: Önder
authors.initials: Ö
authors.lastname: Pekcan
authors.affiliation: Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 124, 10623 Berlin, Germany.
authors.forename: Regine
authors.initials: R
authors.lastname: von Klitzing
authors.affiliation: Istanbul Technical University, Faculty of Science and Letters, Maslak 34469 Istanbul, Turkey. Electronic address: erim@itu.edu.tr.
authors.forename: F Bedia
authors.initials: FB
authors.lastname: Erim
mesh_terms: D000464:Alginates / Q000737:chemistry*; D002412:Cations; D003432:Cross-Linking Reagents / Q000737:chemistry; D055119:Elastic Modulus; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods*; D055595:Mechanical Phenomena; D008670:Metals / Q000737:chemistry*; D008863:Microspheres; D011092:Polyethylene Glycols / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D000464:Alginates; D002412:Cations; D003432:Cross-Linking Reagents; D006603:Hexuronic Acids; D020100:Hydrogels; D008670:Metals; D013501:Surface-Active Agents; D011092:Polyethylene Glycols; D020723:Glucuronic Acid; C515901:Brij 35
keywords: Alginate; Mechanical properties; Surfactant