PROTON BINDING CHARACTERISTICS OF BRANCHED POLYELECTROLYTES

Acid-base properties of branched, weak polyelectrolytes are analyzed t heoretically by means of Ising models with short-range interactions. A ssuming that the structure of the branched polyelectrolyte can be appr oximated by the topology of a tree (no closed loops), the Ising model with nearest neighbor pair interactions can be solved with exact recur sion relations. We demonstrate that the branching structure has import ant implications for the protonation behavior of weak polyelectrolytes . For instance, the protonation a dendritic and a comblike polyelectro lyte proceed rather differently. Within this framework, the titration behavior of branched poly(ethylene imine) can be explained quantitativ ely.