Horizontally and vertically aligned helical conjugated polymers: Comprehensive formation mechanisms of helical fibrillar morphologies in orientation-controlled asymmetric reaction fields consisting of chiral nematic liquid crystals

Abstract

Orientation-controlled asymmetric reaction fields consisting of chiral nematic liquid crystals (N*-LCs) were comprehensively studied to elucidate the formation mechanisms of horizontally and vertically aligned helical polyacetylenes (H-PAs). The alignment of the N*-LC was controlled by tuning the concentration of a chiral molecule added as a chiral dopant to a parent nematic LC and/or by using a rod-like molecule used as a vertical orientation inducer. It was found that the horizontal N*-LC gives rise to horizontally aligned H-PAs, and the vertical N*-LC consisting of two types of multilayered arrangements provides U- and V-shaped fibrillar morphologies of vertically aligned H-PAs. The observed formation mechanisms are useful for understanding asymmetric polymerisations of helical conjugated polymers prepared in chiral nematic or cholesteric liquid crystal reaction fields.