title: Structural response of polyelectrolyte dendrimer towards molecular protonation: the inconsistency revealed by SANS and NMR.
abstract: Polyamidoamine (PAMAM) dendrimers and their charged state in deuterium oxide have been investigated with proton pulsed field gradient diffusion nuclear magnetic resonance (PFG-NMR) and small-angle neutron scattering (SANS) techniques. NMR measurements suggest that significant variation of the hydrodynamic radius, calculated by the Stokes-Einstein relation with appropriate surface conditions, is observed upon increasing the molecular protonation. However, a comparative SANS experiment indicates little dependence of the dendrimer global size, in terms of its radius of gyration, on molecular protonation. The inconsistency indicates the necessity of incorporating the effect of molecular interface modification and molecular porosity provided by dressed counterions, when dynamical measurements are used for the determination of the structural characteristics of ionic soft colloids even in dilute suspensions.
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
authors.forename: Kunlun
authors.initials: K
authors.lastname: Hong
authors.forename: Yun
authors.initials: Y
authors.lastname: Liu
authors.forename: Lionel
authors.initials: L
authors.lastname: Porcar
authors.forename: Dazhi
authors.initials: D
authors.lastname: Liu
authors.forename: Carrie Y
authors.initials: CY
authors.lastname: Gao
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Smith
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Herwig
authors.forename: Sheng
authors.initials: S
authors.lastname: Cai
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Bin
authors.initials: B
authors.lastname: Wu
authors.forename: Wei-Ren
authors.initials: WR
authors.lastname: Chen
authors.forename: Li
authors.initials: L
authors.lastname: Liu
mesh_terms: D050091:Dendrimers / Q000737:chemistry*; D004058:Diffusion; D057446:Hydrodynamics; D009682:Magnetic Resonance Spectroscopy; D033363:Neutron Diffraction; D011522:Protons; D053838:Scattering, Small Angle; D012996:Solutions
chemical_list: D050091:Dendrimers; C104700:PAMAM Starburst; D011522:Protons; D012996:Solutions