Hydrodynamic size and charge of polyelectrolyte complexes.

Area of Science:

• Polymer Science
• Supramolecular Chemistry
• Materials Science

Background:

• Polyelectrolyte complexes (PECs) are formed by electrostatic interactions between oppositely charged polymers.
• PECs have diverse applications in surface modification, flocculation, and sorption of organic molecules.
• Understanding the formation and properties of soluble PECs is crucial for optimizing their applications.

Purpose of the Study:

• To investigate the formation and characteristics of primary polyelectrolyte complexes.
• To determine the hydrodynamic size and effective charge of PECs formed between poly(diallyl dimethyl ammonium chloride) and poly(styrene sulfonate).
• To elucidate the relationship between charge compensation and the physical properties of PECs.

Main Methods:

• Utilized pulsed field gradient nuclear magnetic resonance (PFG-NMR) to measure diffusion coefficients.
• Determined hydrodynamic radius from diffusion coefficients obtained via PFG-NMR.
• Employed electrophoresis NMR to ascertain the effective charge of the polyelectrolytes and their complexes.

Main Results:

• The formation of primary, soluble polyelectrolyte complexes was successfully monitored.
• The hydrodynamic size of the primary PEC was found to be smaller than that of the parent poly(styrene sulfonate).
• A significant reduction in the effective charge of the polyelectrolyte complexes was observed.

Conclusions:

• Charge compensation between oppositely charged polyelectrolytes leads to reduced electrostatic repulsion and smaller complex sizes.
• NMR techniques, particularly PFG-NMR and electrophoresis NMR, are powerful tools for characterizing polyelectrolyte complexes.
• The findings provide fundamental insights into the structure-property relationships of polyelectrolyte complexes, relevant for their application development.