Hierarchy of Periodic Patterns in the Twist-bend Nematic Phase of Mesogenic Dimers

Abstract

Abstract.Several attractive properties of hydrocarbon-linked mesogenic dimers have been discovered, a major feature of these has been the ability of dimers under confinement to form periodic patterns. At least six different types of stripe-like periodic patterns can be observed in these materials under various experimental conditions. Our most recent finding is the discovery of micrometre-scale periodic patterns at the N-N tb phase transition interface, and sub-micrometre scale patterns in the N tb phase. Layer-like sub-micrometre patterns were observed using three-photon excitation fluorescence polarizing microscopy, and these are being reported here.

The dependency of twist-bend nematic liquid crystals on molecular structure: a progression from dimers to trimers, oligomers and polymers

“…More detailed discussion of the optical textures of the N TB phase can be found elsewhere. 66,73 The ability to draw freestanding films of the twist-bend nematic indicates that this mesophase has structural periodicity ( Fig. 5).…”

The stabilisation of the Nxphase in mixtures

“…The correlation with theoretical models is not fully clear and multilevel ordering has been considered and discussed. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Indeed, a considerable theoretical and simulation effort is currently targeted at understanding the liquid crystal phase behaviour in systems with conformational chirality. Due to these questions, in this contribution the phase is termed N x .…”

The design and investigation of the self-assembly of dimers with two nematic phases

“…The optical defect textures of the N x phase are distinctly different to that of a typical nematic and are more reminiscent of those of smectic phases. 12 The crucial experiment to distinguish between an N x and a layered phase are XRD studies, where the absence of intensities associated with layering conrms the nematic character. Theoretical research quickly associated this low temperature nematic phase with potential splay bend and twist bend structures 13 and this was developed in more detail theoretically as well as in simulation studies.…”