Influence of polydispersity on the isotropic-nematic boundary in melt of semiflexible diblock copolymer

The analytical expressions have been obtained to describe the dependence of spinodal curve at which isotropic state of polydisperse melt of semiflexible diblock copolymer becomes unstable with respect to formation of nematic state on the polydispersity indices of the blocks, parameters of anisotropic interactions, and flexibility of blocks. The flexibility of blocks is taken into account within discrete worm-like chain model, lengths of blocks are assumed to be distributed by the Schulz–Zimm distribution. It is shown that increase of degree of polydispersity of blocks yields the increase of nematic spinodal temperature.

A note on scenarios of metastable water

A recently developed molecular-based equations of state for water are analyzed with respect to the behavior of the liquid spinodal curve. It is shown that all of them yield the spinodal exhibiting a minimum in accordance with Speedy’s stability-limit conjecture and with the behavior predicted by the accurate (but purely empirical) IAPWS-95 equation. It means that the considered equations of state give consistent results but qualitatively different from those resulting from available computer simulations, which yield a monotonic spinodal line.