title: On the percolation of alginate/calcium systems at low concentrations.
abstract: The sol-to-gel transition of an alginate rich in β-d-mannuronic acid residues and at a concentration of 0.1% w/v in 15 mM NaCl in the presence of calcium ions of 0 to 3.5mM was studied with dynamic light scattering. The dynamics of the different systems added further insight into the alginate gel forming mechanisms. Below a Ca(2+) concentration of 0.7 mM, the build-up of small aggregates could be verified. Moreover, at a critical concentration, close to 0.9 mM Ca(2+), a percolated, non-ergodic network started to form from some of these aggregates, with smaller aggregates still diffusing in the network. The system displayed strong non-ergodicy at high Ca(2+) concentrations with a non-ergodicity parameter that appeared to form discontinuously from near zero to a clearly non-zero value at the critical Ca(2+) concentration.
authors.affiliation: Applied Chemistry, Chemical and Biological Engineering, Chalmers University of Technology, S-412 96 Göteborg, Sweden.
authors.forename: Adele
authors.initials: A
authors.lastname: Khavari
authors.affiliation: Applied Chemistry, Chemical and Biological Engineering, Chalmers University of Technology, S-412 96 Göteborg, Sweden.
authors.forename: Jan-Erik
authors.initials: JE
authors.lastname: Löfroth
authors.affiliation: Department of Chemistry and Molecular Biology, University of Gothenburg, S-412 96 Göteborg, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Bergenholtz
authors.affiliation: Department of Energy and Resources, University College London, 220 Victoria Square, Adelaide, SA 5000, Australia. Electronic address: m.nyden@ucl.ac.uk.
authors.forename: Magnus
authors.initials: M
authors.lastname: Nydén
keywords: Alginate; Dynamic light scattering; Gel; Structure dynamics