Phase transitions in polypeptide liquid crystals: (T,φ) phase diagram including the reentrant isotropic phase

Publisher Website
Google Scholar
Abstract
The phase diagram of polybenzyl‐L‐glutamate in a denaturant solvent mixture of dichloroacetic acid/dichloroethane has been mapped as a function of temperature and volume fraction of polymer. This polymer solution exhibits a reentrant isotropic phase at low temperatures where a conformational change in the macromolecule occurs. The liquid crystal is bordered by a low and high temperature biphasic zone where isotropic and anisotropic components are in equilibrium. The lower temperature biphasic region is broadened over that at high temperatures by the coexistence of random coils and polymer helices. Optical rotatory measurements in dilute solution distinguish between two conformationally different isotropic phases of this polymer, one with orientationally disordered helices and the other consisting of random coils.