Cholesteric lyotropic liquid crystals and thermally reversible gels from polyisocyanates

The Flory phase diagram for solutions of rod-like polymers reveals two possibilities for the formation of liquid crystal states. One involves high concentrations of polymer in good solvents and the other dilute solutions in poor solvents. We have taken both routes for poly(alkyl isocyanates). In the former route, we have developed a thermodynamic theory to gain insight into the chirality source of the twisting, and have also tested the possibility of a polymer conformational response to the liquid crystal ordering. By the latter route we encounter thermally reversible gels with unusual chiroptical properties.