Helical Polyacetylene: Asymmetric Polymerization in a Chiral Liquid-Crystal Field

The carbonizations of H-PA films by way of iodine doping afford carbon and graphitic films which completely preserve morphologies and even helical nanofibril structures, were studied. The novel tetrasubstituted LC axially chiral binaphthyl derivatives with high helical twisting powers were explored to be useful for inducing highly twisted nematic liquid crystal (N*-LC). The liquid crystallinity of the chiral dopant has no direct influence on the helical twisting power of the N*-LC; it plays the important role of increasing the miscibility of the chiral dopant to host N-LC, leading to an increase of the upper limit in concentration of the chiral dopant. It is found that the highly screwed N*-LC with a helical pitch of 270 nm depresses the formation of the bundle of fibrils of H-PA, resulting in a bundle-free fibril morphology consisting of single fibrils. This indicates that the degree of screwing in the N*-LC is a key factor to control the bundle formation and/or depression in the fibril morphology of H-PA.