Monte Carlo study of polyelectrolyte behavior. II.

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Abstract
A Monte Carlo simulation of an isolated polyelectrolyte chain in the presence of its counter ions without added salt is reported. Configurational properties such as the mean square end-to-end distance 〈R2N〉, the mean square radius of gyration 〈S2N〉, and the mean reduced electrostatic energy 〈UNI/NIkT〉, were studied as a function of the ionic strength of the solution, C; and the % charge of the chain. System behavior is classified into three regions: I: κ−1≪〈S2N〉1/2; II: κ−1∼1/2<S2N〉1/2; III: κ−1≫〈S2N 〉1/2, where κ−1 is the Debye–Hückel radius describing the scale of order of interionic interactions. In region I, the polyelectrolyte behaves configurationally as a random coil and the system is describable electrically as a simple electrolyte. In region II, the polyelectrolyte undergoes a conformational transition and the system electrically deviates notably from simple electrolyte behavior. In region III, the polyelectrolyte behaves configurationally as a rod and the system is characterized electrically by 〈UNI/NIkT〉≳0.