Viscosometric investigation of the ordinary–extraordinary phase transition in dilute polylysine solutions

Low shear viscosities have been determined for a 1 mg/ml poly(L‐lysine) solution as a function of added salt concentration in the region of the previously reported ordinary–extraordinary phase transition. The measured viscosities indicate that the polyions are far from completely extended at the transition. Estimates of the longest internal relaxation time for an equivalent free‐draining Rouse‐Zimm chain give τ ≃ 10−5 sec, similar to that of the rapid, angle‐independent component previously observed in the dynamic light‐scattering correlation function at the transition. An unusual peak and valley are observed in the curve of [η]0 versus [NaBr] in the transition region. Possible interpretations of these features, and their bearing on the nature of the extraordinary phase, are discussed.