Block Copolymers Containing Polyisocyanate Segments

Polyisocyanates are comprised of only amide bonding in the main chain and maintain their helical rod structures, so they normally show liquid crystallinity or high crystallinity. For instance, the helix conformation (12/5) of poly(hexylisocyanate) (PHIC) and its high crystallinity in the solid state are well observed by X-ray scattering (Wu et al., 1992). PHIC displays rod structures with a very long persistence length of 50-60 nm in the solution state (Bur and Fetters, 1976). It also shows lyotropic liquid-crystalline behavior at high concentrations (Aharomi, 1979 Aharoni and Walsh, 1979). 

In contrast to homopolymers, interesting new supermolecular structures are expected when a flexible coil segment is connected to a rigid polyisocyanate rod, because the molecules impart 

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