COEXISTENCE OF 2 LIQUID-CRYSTALLINE PHASES IN POLY(GAMMA-BENZYL-ALPHA,L-GLUTAMATE) SOLUTIONS

IN 1956, Flory1 proposed a phase diagram for rod-like molecules of the form shown in Fig. 1. Since then, most of the major features of this diagram have been verified experimentally2. In particular, the two-phase 'chimney' is now well established. One feature that has not previously been established, however, is the slight maximum (the 'cap') in the phase boundary on the high-concentration side of the chimney. Flory1 pointed out that this cap should manifest itself as two coexisting liquid-crystalline (anisotropic) phases. Here we provide evidence for bulk phase separation into two such phases in a macroscopic (∼0.5 g) liquid-crystal sample held in a constant-temperature bath. A distinct boundary can be seen between the two phases, and they are distinguished further under an optical polarizing microscope. © 1990 Nature Publishing Group.