Phase behaviour and structure of stable complexes of oppositely charged polyelectrolytesV. Mengarelli1, L. Auvray2 and M. Zeghal1
1 Laboratoire de Physique des Solides, UMR CNRS 8502, Bât. 510 Université Paris-sud - 91405 Orsay, France, EU
2 Institut de Chimie des Matériaux Paris Est UMR CNRS 7182, Equipe Matériaux Polymères aux Interfaces, Université d'Évry - 91025 Évry, France, EU
received 17 October 2008; accepted in final form 5 February 2009; published March 2009
published online 16 March 2009
We study the formation and structure of stable electrostatic complexes between oppositely charged polyelectrolytes, a long polymethacrylic acid and a shorter polyethylenimine, at low pH, where the polyacid is weakly charged. We explore the phase diagram as a function of the charge and concentration ratio of the constituents. In agreement with theory, turbidity and potential measurements show two distinct regimes of weak and strong complexation, which appear successively as the pH is increased and are separated by a well-defined limit. Weak complexes observed by neutron scattering and contrast matching have an open, non-compact structure, while strong complexes are condensed.
82.35.Rs - Polyelectrolytes.
61.25.he - Polymers solutions.
61.05.fg - Neutron scattering (including small-angle scattering).
© EPLA 2009