Indication of a twist-grain-boundary-twist-bend phase of flexible core bent-shape chiral dimers.

The effect of the molecular chirality of chiral additives on the nanostructure of the twist-bend nematic (N-TB) liquid crystal phase with ambidextrous chirality and nanoscale pitch due to spontaneous symmetry breaking is studied. It is found that the ambidextrous nanoscale pitch of the N-TB phase increases by 50% due to 3% chiral additive, and the chiral transfer among the biphenyl groups disappears in the N-TB* phase. Most significantly, a twist-grain boundary (TGB) type phase is found at c > 1.5 wt% chiral additive concentrations below the usual N* phase and above the non-CD active N-TB* phase. In such a TGB type phase, the adjacent blocks of pseudo-layers of the nanoscale pitch rotate across the grain boundaries.