title: Temperature-induced formation of strong gels of acrylamide-based polyelectrolytes.
abstract: Very strong physical gels have been formed by moderate temperature increases of concentrated aqueous dispersions of acrylamide-based copolymers. The results of rheometry, confocal laser scanning microscopy, and differential scanning calorimetric studies of acrylamide-based copolymers with acrylic acid (poly[AM-AA]) and the sodium salt of 2-acrylamido-2-methylpropane acid (poly[AM-NaAMPS]) suggest that the temperature-induced swelling of the polymer beads and dissolved chains creates strongly entangled polymer networks above the upper critical solution temperature. Analysis of the viscoelastic response showed that the time scale for the gelation process is about minutes to hours. The addition of high concentrations of Ca(2+) resulted in a significant reduction in the modulus.
authors.affiliation: Material Chemistry Research Group, Department of Physical Inorganic and Structural Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Ranjith Krishna
authors.initials: RK
authors.lastname: Pai
authors.forename: Jovice B S
authors.initials: JB
authors.lastname: Ng
authors.forename: Saju
authors.initials: S
authors.lastname: Pillai
authors.forename: Lennart
authors.initials: L
authors.lastname: Bergström
authors.forename: Niklas
authors.initials: N
authors.lastname: Hedin