title: Water dynamics in rigid ionomer networks.
abstract: The dynamics of water within ionic polymer networks formed by sulfonated poly(phenylene) (SPP), as revealed by quasi-elastic neutron scattering (QENS), is presented. These polymers are distinguished from other ionic macromolecules by their rigidity and therefore in their network structure. QENS measurements as a function of temperature as the fraction of ionic groups and humidity were varied have shown that the polymer molecules are immobile while absorbed water molecules remain dynamic. The water molecules occupy multiple sites, either bound or loosely constrained, and bounce between the two. With increasing temperature and hydration levels, the system becomes more dynamic. Water molecules remain mobile even at subzero temperatures, illustrating the applicability of the SPP membrane for selective transport over a broad temperature range.
authors.affiliation: Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA.
authors.forename: N C
authors.initials: NC
authors.lastname: Osti
authors.affiliation: Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA.
authors.forename: T N
authors.initials: TN
authors.lastname: Etampawala
authors.affiliation: Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA.
authors.forename: U M
authors.initials: UM
authors.lastname: Shrestha
authors.affiliation: Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA.
authors.forename: D
authors.initials: D
authors.lastname: Aryal
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
authors.forename: M
authors.initials: M
authors.lastname: Tyagi
authors.affiliation: Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: S O
authors.initials: SO
authors.lastname: Diallo
authors.affiliation: Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: E
authors.initials: E
authors.lastname: Mamontov
authors.affiliation: Chemical and Biomolecular Engineering Department, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Cornelius
authors.affiliation: Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA.
authors.forename: D
authors.initials: D
authors.lastname: Perahia