Following the polyisocyanate helix reversal from dilute solution through the liquid crystal and into the solid state

The absence of a predetermined helical sense in the polyisocyanates causes the formation of helix reversals which enforce a strong cooperativity for the amplification of chiral effects. The helix reversals though also place a limit on this amplification, a limit which would be eliminated by reducing the helix reversal population. Approaching the liquid crystal state of the polyisocyanates in both dilute and concentrated solutions appears to cause the exclusion of the helix reversals which is consistent with theoretical expectations. Since the linear birefringence of the polyisocyanate solid state precludes optical activity measurements associated with the polymer, we have synthesized hydrogen bonding side chain adapted polyisocyanates which appear by DSC and infra-red criteria to form equilibrium molecular composites with copolymers of vinyl phenol and styrene. The optical activity properties of these composites may offer a new way to probe polymer motion in the solid state.