EXACT AFFINITY DISTRIBUTIONS FOR LINEAR POLYAMPHOLYTES AND POLYELECTROLYTES

Ising models have been used to describe acid-base behavior of linear p olyampholytes and polyelectrolytes. Alternatively, such titration curv es are often interpreted in terms of an affinity distribution (pK spec trum). Here we show that such affinity distributions exist if the zero s of the grand partition function of the corresponding Ising model are negative and real. Furthermore, we derive the exact affinity distribu tions for various Ising models of linear polyelectrolytes and polyamph olytes. Applications of the Ising model to the titration behavior of p oly(acrylic acid) and poly(ethylenimine) are discussed. (C) 1996 Ameri can Institute of physics.