Catalytic Action of Polyelectrolytes

Abstract

The recent advancement in the study on the catalytic influences of polyelectrolytes was reviewed with 73 references. Polyelectrolyte influence (both acceleration and deceleration) on ionic reactions, which is much larger than the simple electrolyte effect, is explained with the changes of the rate constant induced by high electrostatic potentials of macroions. The quantitative discussion is carried out by using the Lifson-Katchalsky and Manning theories for the dilute polyelectrolyte solutions. In addition to the electrostatic interactions, the contributions of hydrophobic, hydrogen-bonding and charge-transfer interactions are dissected for a variety of combinations of "catalyst" polyelectrolytes and reactants. Polyelectrolyte influence on elementary processes is discussed for equilibrium reactions. The forward and backward steps are affected in a different proportion; the use of the term "polyelectrolyte catalysis" is not justified. The polyelectrolyte acceleration of interionic reactions is shown to be associated with decreases in the entropy and enthalpy of activation. The desolvation of the ions by the electrostatic field of macroions is discussed.