Polyelektrolyt

Polyelektrolyt, or polyelectrolyte in English, refers to a polymer that contains multiple ionizable groups along its chain. In aqueous solution these groups can dissociate, yielding a charged polymer backbone and counterions. Polyelectrolytes can be polycations (positively charged), polyanions (negatively charged), or polyampholytes when the chain carries both types of charges. They can be synthetic, such as polyacrylates or poly(diallyldimethylammonium) salts, or natural, including DNA, heparin, alginates, and certain proteins.

Strong polyelectrolytes dissociate largely regardless of pH, whereas weak polyelectrolytes have ionization levels that depend on pH and ionic strength. The high charge density along the chain leads to pronounced electrostatic interactions, extended chain conformations in solution, and significant effects on solution viscosity and osmotic pressure. Salt ions screen charges, reducing repulsion and promoting coil compaction. Counterions may condense near the chain, effectively lowering the net charge.

Polyelektrolyt form complexes with oppositely charged polymers or biomolecules, a phenomenon exploited in complex coacervation and in gene delivery, where cationic polyelectrolytes condense DNA. They also serve as rheology modifiers, thickening agents, flocculants in water treatment, stabilizers in cosmetics and foods, and components in various coatings and materials.

Characterization commonly includes zeta potential, electrophoretic mobility, light scattering to assess size and charge, and rheological measurements to determine viscosity changes with concentration and salt. Safety and environmental considerations vary by type; some synthetic cationic polyelectrolytes can pose toxicity concerns, while natural polyelectrolytes are often more biodegradable.