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Author (up) Boue, F.; Combet, J.; Deme, B.; Heinrich, M.; Zilliox, J.G.; Rawiso, M. openurl 
  Title SANS from Salt-Free Aqueous Solutions of Hydrophilic and Highly Charged Star-Branched Polyelectrolytes Type Journal Article
  Year 2016 Publication Polymers Abbreviated Journal Polymers  
  Volume 8 Issue 6 Pages 19 pp  
  Keywords electrostatics; polyelectrolytes; star polymers; Small Angle Neutron Scattering; scattering peak; Debye length; scaling laws; counterions; condensation; semi-dilute; interpenetration; overlap concentration  
  Abstract Scattering functions of sodium sulfonated polystyrene (NaPSS) star-branched polyelectrolytes with high sulfonation degrees were measured from their salt-free aqueous solutions, using the Small Angle Neutron Scattering (SANS) technique. Whatever the concentration c, they display two maxima. The first, of abscissa q(1)*, is related to a position order between star cores and scales as q(1)* c(1/3). The second, of abscissa q(2)*, is also observed in the scattering function of a semi-dilute solution of NaPSS linear polyelectrolytes. In the dilute regime (c < c*, non-overlapping stars), peak abscissa does not depend on concentration c and is just an intramolecular characteristic associated with the electrostatic repulsion between arms of the same star. In the semi-dilute regime, due to the star interpenetration, the scattering function – through the peak position, reflects repulsion between arms of the same star or of different stars. The c threshold between these distinct c-dependencies of q(2)* in the dilute and semi-dilute regimes is estimated as c*. Just as simple is the measurement of the geometrical radius R of the star obtained from the q(1)* value at c* through the relation 2R = 2/q(1)*. By considering NaPSS stars of the same functionality with different degrees of polymerization per arm N-a, we find R scaling linearly with N-a, suggesting an elongated average conformation of the arms. This is in agreement with theoretical predictions and simulations. Meanwhile the value of q(2)* measured in the dilute regime does not allow any inhomogeneous counterion distribution inside the stars to be revealed.  
  Address [Boue, Francois] CE Saclay, CEA, CNRS, Lab Leon Brillouin, F-91191 Gif Sur Yvette, France, Email: francois.boue@grignon.inra.fr;  
  Corporate Author Thesis  
  Publisher Mdpi Ag Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2073-4360 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000379860500026 Approved no  
  Call Number Admin @ benzerara @ Serial 14038  
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