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Updated: May 29, 2026
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Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
Phase behavior and structure of stable complexes between a long polyanion and a branched polycation
Valentina Mengarelli1, Mehdi Zeghal, Loïc Auvray
1Laboratoire de Physique des Solides, CNRS-UMR8502, Université Paris-sud, F-91405 Orsay, France.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|September 21, 2011
Summary
Branched polyethylenimine (BPEI) and polymethacrylic acid (PMA) form stable complexes through pH-controlled association. Two distinct complexation regimes, weak and strong, were observed, with overcharging phenomena analyzed.
Area of Science:
- Polymer Science
- Supramolecular Chemistry
- Materials Science
Background:
- Investigating polyelectrolyte complexation is crucial for understanding polymer interactions and developing new materials.
- Branched polyethylenimine (BPEI) and polymethacrylic acid (PMA) are oppositely charged polymers with pH-dependent behavior.
Purpose of the Study:
- To explore the association between BPEI and PMA in dilute solutions.
- To elucidate the mechanisms and structural characteristics of polyelectrolyte complex formation.
- To analyze the influence of pH on complexation and overcharging phenomena.
Main Methods:
- Turbidimetric titration to monitor complex formation.
- Electrophoretic mobility measurements to determine charge characteristics.
- Small-angle neutron scattering (SANS) for structural analysis at higher concentrations.
Main Results:
- Complexation is pH-controlled, leading to soluble and stable positively charged complexes.
- Two distinct regimes of complexation were identified: weak and strong.
- Weak complexation involves binary complexes, while strong complexation results in condensed aggregates with overcharging.
Conclusions:
- The BPEI-PMA complexation is a cooperative process with distinct weak and strong regimes.
- Overcharging and the observed structures are consistent with current polyelectrolyte theories.
- The study provides insights into the structural evolution of polyelectrolyte complexes from dilute to condensed states.
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