Polyelectrolyte - Polyelectrolyte Conformation

Polyelectrolyte Conformation

The conformation of any polymer is affected by a number of factors: notably the polymer architecture and the solvent affinity. In the case of polyelectrolytes, charge also has an effect. Whereas an uncharged linear polymer chain is usually found in a random conformation in solution (closely approximating a self-avoiding three-dimensional random walk), the charges on a linear polyelectrolyte chain will repel each other (Coulomb repulsion), which causes the chain to adopt a more expanded, rigid-rod-like conformation. If the solution contains a great deal of added salt, the charges will be screened and consequently the polyelectrolyte chain will collapse to a more conventional conformation (essentially identical to a neutral chain in good solvent).

Polymer conformation of course affects many bulk properties (such as viscosity, turbidity, etc.). Although the statistical conformation of polyelectrolytes can be captured using variants of conventional polymer theory, it is in general quite computationally intensive to properly model polyelectrolyte chains, owing to the long-range nature of the Coulomb interaction. Techniques such as dual polarisation interferometry can be used to study polyelectrolyte conformation and conformational changes.